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Effects of size and static temperature exposure on the shear strength of tungsten bonded CFC blocks for divertor in JT-60SA
No full textThe construction of a satellite tokamak, JT-60SA, was completed in 2020. JT-60SA is expected to contribute the research of ITER and developments for DEMO. JT-60SA employs carbon and carbon fiber strengthened carbon (CFC) composites divertors. The divertors will be set on an actively cooled cassette and be remotely handled because of human access restriction into the vacuum vessel due to the radioactivation caused by repeated deuterium plasma operations. An important mission of JT-60SA is high-β steady state plasma research, and during the mission, the use of carbon divertors will be continued. The possibility of metal wall experiments after the complete of high-β steady state plasma research is under discussion. Then the use of remote handled divertor cassette will be a condition, therefore, high performance and appropriate weight divertors are convenient for the operation. One idea is to use clad plates of tungsten and CFC. In previous researches revealed that a sinter bonding method using an insert material of SiC powders + additives was able to join W and CFC. But the research accidentally found out the insert material without explore of the other materials and the size of specimens was small. In present research, some candidates for the insert material were investigated and also the uniformity of strength on a W/CFC block of the expected size were evaluated.journal articl
Modeling and experimental evaluation of the stepping characteristic on a walking-type piezoelectric actuator
Get PDFAiming at the suppression of backward motion, a walking-type piezoelectric actuator was developed in this paper. Two walking modes of ellipse-shaped walking and rhombus-shaped walking were discussed. The dynamic models in the x and y direction were established to simulate the stepping characteristics of two walking modes. The simulated results depicted that the actuator was able to achieve stepping displacement free of backward motion. A prototype was fabricated, and a series of experiments were conducted. The experiments indicated that, under two walking modes, there was a backward displacement in each operating cycle due to assembly errors. To suppress backward motion, a solution to compensate for the assembly errors by varying the bias voltage difference between two stators was proposed. After correcting the assembly errors, the backward displacements were almost eliminated and reduced by 71.4% from 0.28 to 0.08 μm and 68.1% from 0.22 to 0.07 μm, respectively under the ellipse-shaped walking mode and rhombus-shaped walking mode, which proved the effectiveness of the proposed actuator.journal articl
Fluorite-type materials in the monolayer limit
Get PDFThe 2H, 1T, and their distorted structures are known as prototype structures of AB2 monolayers. Here, we study a puckered (PCK) structure that is truncated from the (110) surface of fluorite-type materials. 53 fluorite-type materials are investigated based on first-principles approach. The formation energy calculations indicate that seven systems form the PCK structure in the monolayer limit, while other systems form either 1T, 2H, or distorted 1T structures. The PCK structures of PbF2 and Ga2Au exhibit negative Poisson’s ratio (NPR) in the out-of-plane direction. We explain the NPR by an analytical model assuming a constant interatomic distance under the in-plane strain. In addition, we demonstrate that the appearance of NPR is correlated with non-ionic character of the system, which is based on the surface energy calculations and the Born effective charge analyses. We also find that PRh2 in the PCK structure is highly distorted.journal articl
The Change of Infection Prevention and Psychosomatic States ofStudents at Muroran Institute of Technology during COVID-19 -A Latent Class Analysis-
Get PDFThe behavior of Infection Prevention and Psychosomatic state of Students at Muroran Institute of Technology during Covid-19 period between 2020 and 2023 are estimated by general statistical analysis and a latent class analysis. The results indicate that there is no clear difference by years, however students were shown to be sensitive to the policies of the university and the government, and to react as best they could in their own lifestyles. Stress might divide their way to react.departmental bulletin pape
オンラインと教室でのコミュニケーション型言語学習に対する学生の認識に関する調査。
Get PDFThis paper presents the results from a study focused specifically on EFL classes that used a communicative language teaching (CLT) approach. The aim of the survey was to explore students’ attitudes to both online and in-classroom communicative English language learning, and subsequently consider what implications these would have for student learning and teacher pedagogy. This survey undertook an investigation of students’ attitudes to various aspects of communicative language learning in both classroom and online settings. A sample of 327 non-English major students at a science and engineering university completed a Likert scale-based questionnaire measuring their attitudes in five categories: English study; Online learning; Learning environment; Lesson activities; and Teacher engagement. Analysis of the survey data show that students clearly prefer in-class language learning. Students considered the classroom-based pedagogy to be more effective, particularly in terms of peer involvement and interaction. Findings from the survey have significant implications for how students experience communicative language learning and how teachers can best enhance this experience.journal articl
汚泥処理設備における機械学習を活用した自動制御に関する研究
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）わが国の下水道事業は，財政面および運転の体制面において様々な問題を抱えている．特に職員数の問題に対して，5年後にベテランオペレータの大量退職が予想されており，現在の運転体制を維持できない恐れがある．この問題に対して，国土交通省は下水道に関するAIを活用した運転操作デジタルトランスフォーメーション検討会を行うなど，運転操作の自動化や効率化に向けた取り組みを積極的に推進している．
本研究では，機械学習やディープラーニングを活用し，汚泥処理設備における自動運転を目指す．具体的には，これまで経験を積んだオペレータによる運転操作を完全自動化し，目標値に対する制御性能および資源使用量の効率化の面から評価を行った．対象とする設備は，脱水設備と焼却設備が一体となった創エネルギー型脱水焼却システムであり，それぞれの設備において手動介入が必要な運転箇所の自動化および効率化を試みた．
脱水設備では，適切なフロック状態を維持するため，オペレータがフロックを目視確認することでポリマー注入量を調整し，設備を安定化させていた．これに対して，画像からフロック状態を推定し，最適なポリマー注入量を制御するシステムの開発を行った．具体的には，セマンティックセグメンテーションを用いてフロック間の間隙面積を算出し，間隙面積をフロック状態の推定値とした．この間隙面積を使用したポリマー注入量の自動制御を実現し，オペレータの運転実績と比較したところ，制御性能およびユーティリティ使用の効率性の両面において優れていることを明らかにした．
一方，焼却設備は焼却炉内温度の安定化を目指した手動運転が行われている．炉内温度の安定化は，脱水汚泥の搬送・滞留時間を考慮した上で，焼却炉に適した含水率となるよう脱水機を運転する必要がある．これに対して，焼却炉の燃焼傾向を予測するモデル予測制御と脱水汚泥の含水率を機械学習によって予測し，脱水機を制御するシステムを組み合わせたカスケード型制御を構築した．本カスケード型制御は，炉内温度の傾向を予測するとともに燃焼に適した含水率を出力し，出力された含水率となるように脱水機の制御を行うシステムとなっている．ここでは有用性を検証するため，オペレータの運転実績と比較
を行った．結果として，制御性能の面とユーティリティの使用面において優れていることを明らかにしたOur country’s sewage works are facing various problems in terms of financial and operational management. Particularly regarding the problem of operator numbers, a mass retirement of veteran operators is anticipated in five years, raising concerns about the ability to maintain the current operational system. Particularly regarding the problem of operator numbers, a mass retirement of veteran operators is anticipated in five years, raising concerns about the ability to maintain the current operational structure.
For this problem, the Ministry of Land, Infrastructure, Transport and Tourism is actively promoting initiatives aimed at automating and streamlining operational management, including conducting a study group on digital transformation utilizing AI related to sewage plant.
In this study, we aim to achieve automated operation of sludge treatment plants by utilizing machine learning and deep learning techniques. Specifically, the study evaluated the full automation of operational management previously performed by experienced operators, assessing control performance against set values and the efficiency of resource usage. The experimental plant is an innovative energy-generating sludge treatment system that combines dewatering and incineration process. Efforts were made to automate and optimize the points that require manual operation in each piece of process.
In the dewatering process, to maintain an appropriate floc condition, operators adjusted the polymer dosage based on visual confirmation of the floc, thereby stabilizing the plant. We developed a system that estimates the floc condition from images and controls the optimal polymer dosage. Specifically, we calculated the area of gap between flocs using semantic segmentation and constructed an automated polymer dosing system based on the gap area. When compared to manual operation by operators, this system achieved superior results in terms of control performance and efficiency of utility usage.
On the other hand, manual operation of the incineration process is conducted with the aim of stabilizing the internal temperature of the incinerator. To stabilize the internal temperature of the incinerator, the dewatering process must be operated to achieve a moisture content appropriate for the incinerator, taking into account the transport and retention time of the dewatered sludge. We constructed a cascaded control system that combines model predictive control for predicting the combustion tendencies of the incinerator with a system that controls the dewatering equipment based on the moisture content of the dewatered sludge predicted by machine learning. The system was compared to manual operation by the operator and was superior in terms of control performance and utility usage.doctoral thesi
Phonology of the Diphthongs in Modern Icelandic− Particular Focus on the Interpretation of their ‘Length’ −
Get PDFA large number of coursebooks in Icelandic and in its pronunciation have been published so far, and quite a few studies on Icelandic phonetics and phonology have also been made. In these books and articles, it is often mentioned that Icelandic has both long and short diphthongs. Although the quantity distinction in diphthongs seems now an established belief in Icelandic language teaching and linguistics, surprisingly few attempts have been made so far at exploring the phonemic nature of the length distinction in the Icelandic diphthongs. Besides, little attention has been paid to diphthongs in the phonology of Icelandic and the question about the phonemics nature of diphthongs still remains unsettled. To solve these issues, the author has conducted field researches and acoustic analyses of the Icelandic diphthongs, and based on the evidence obtained through those researches and analyses, the author draws a conclusion that the diphthongs in Icelandic are phonemically combinations of a vowel and consonants, not autonomous diphthongal phonemes, and that the quantity distinction in the diphthongs is not a phonemic but phonetically conditioned or context-dependent phenomenon.departmental bulletin pape
RESEARCH OF SPATIAL IMAGING TECHNOLOGY ON SUPPORTS OF IMPROVEMENT AND MANAGEMENT FOR MEDIUM AND SMALL RIVERS
Get PDF本研究の目的は，中小河川の整備及び管理を実現するための空間イメージング技術を開発することである．中小河川の整備は，通常時の利用や環境の保全再生及び洪水時の安全確保に加え，地域の意向を反映した整備が求められ，将来像が直感的にイメージ化できる技術が必要である．本研究では，現在河川改修中の北海道室蘭市を流れる知利別川を対象とし，地域住民の意向をワークショップで把握し，VR による河川空間デザインを実施した．また，洪水時の危険性を想起させる活用を見据え，iRICNays2Floodによる増水や氾濫の計算結果をVRでイメージ化した．結果として，①地域の意向を勘案した河川空間デザインの作成手法，②平常時から異常時までのシームレスな画像表示手法，③情報が限定される中小河川への技術展開が可能な手法を提案した．The aim of this study was to develop spatial imaging technology to assist in the development and management of small and medium sized watercourse infrastructure. The watercourse infrastructure should facilitate daily water usage, protect or restore riverine ecosystems, ensure safety in times of flooding, and incorporate community preferences. The study focused on the Chiribetsu River, an under-repair watercourse in Muroran, Hokkaido. A focus group was formed to ascertain the residents’ attitudes toward the river. Based on the findings, a virtual environment of the Chiribetsu River was created. The purpose was to use this virtual content as a means to remind residents about flood threats. The content incorporated information on river swelling and overflow scenarios, estimated using iRICNays2DFlood. In light of the results, the following recommendations are made: 1) Resident opinions should be considered when developing virtual watercourse environments; 2) The virtual environment should feature a seamless visual transition from normal conditions to an emergency scenario; and 3) The virtual-reality technology should be compatible with small and medium watercourses, for which information may be limited.journal articl
実規模衝撃荷重載荷実験に基づいた落石防護柵支柱の根入れ深さ決定法に関する研究
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）我が国の山岳部や海岸線などの急崖斜面に隣接する道路沿いには，落石などから人命や交通網を守るために数多くの落石対策工が設置されている。その対策工の１つである落石防護柵は，落石防護擁壁天端に設置する場合が多く，その場合には擁壁が無筋コンクリート構造であることにより，支柱の定着方法が課題となる。現行設計は，落石衝突による動的挙動特性は考慮せずに，静力学に基づいて行われている。これより，現行設計法の妥当性を検証するとともに，衝撃荷重載荷時における動的挙動特性を考慮した合理的な設計法を確立することは，喫緊の課題であるものと判断される。
このような観点から，本研究では落石衝撃荷重載荷時における無筋コンクリート擁壁中に埋設された落石防護柵支柱の合理的な根入れ深さ決定法を確立することを目的として，我が国で最も多く採用されている高さが 2 m の実規模擁壁と柵高が 2 m の防護柵支柱を用いた静荷重のみならず衝撃荷重載荷実験を実施して，検討を行った。
第１章は本論文の序論であり，本研究の背景や既往の研究，及び本論文の目的と概要について述べている。
第２章及び第３章では，防護柵支柱の必要根入れ深さを概略的に明らかにすることを目的に，防護擁壁中に支柱を貫通させた場合を対象に実施した静荷重及び衝撃荷重載荷実験結果について述べている。検討の結果，支柱を貫通させた場合には根入れ深さが 650 mm 程度で完全定着状態に至ることを明らかにしている。
第４章及び第５章では，支柱を貫通させた場合における必要定着長を参考に，根入れ深さを 700, 500, 300 mm に変化させた場合を対象に実施した静荷重及び衝撃荷重載荷実験結果について述べている。検討の結果，必要根入れ深さは 500 mm 程度であることを実験的に明らかにしている。また，実験結果に基づき，現行設計法の妥当性に関する検討を行うと共に動的挙動特性を考慮した必要根入れ深さに関する照査式を提案している。
第６章では，擁壁の断面形状や支柱の断面剛性が変化した場合にも支柱の必要根入れ深さを適切に評価可能な弾塑性衝撃応答解析手法を提案し，実験結果と比較する形でその妥当性について述べている。
第７章は本論文の結論であり，本研究で得られた知見を整理している。In order to protect human lives and transportation networks from falling rocks, many rockfall protection facilities such as retaining walls and fences constructed along the road next to steep cliffs and slopes in mountainous areas and/or along coastal lines. Normally, the rockfall protection fences are mounted on the top of the protection retaining wall constructed as a gravity-type plain concrete structure. Even though anchoring depth of the posts for the fence embedded into the retaining wall is designed based on statics, those dynamic response characteristics have not been considered. It may be important to investigate an applicability of the method to those under the impact loading.
From this point of view,
in order to establish a rational design method for anchoring depth of the posts for the rockfall protection fences mounted on the plain concrete retaining walls under impact loading, proto-type static and impact loading tests for the 2 m high posts mounted on the 2 m high retaining walls which are frequently constructed in Japan, were conducted. The tests were conducted varying anchoring depth of the posts: 700 mm, 500 mm, and 300 mm, based on the results of the preliminary experiments for the case of the fully embedded posts into the walls. A 1,000 kg steel weight was impacted at the location of 400 mm height from the top surface of the wall for the posts as to behave with coupling between bending and shearing actions. Also, an elastic-plastic FE analysis method was proposed to precisely predict the anchoring depth of the posts in the cases of the wall with different dimensions and/or the post with different flexural stiffness from those of the tested in this study, and the applicability was investigated comparing with the experimental results.
From this study, following results were obtained: 1) the posts may reach the ultimate state for the wall to collapse with punching shear failure due to the cracks developing from the edges of the loading-side flange; 2) the anchoring depth for the posts may be required to take approximately 500 mm; 3) the depth should be determined considering only punching shear failure of the wall at when the rock impacts near the top-surface of the wall; 4) the current design specification may give more conservative value than the experimental results, and 5) the required anchoring depth of the post can be better predicted by using the proposed numerical analysis method.doctoral thesi
キーワード法の探検
Get PDFThe current mixed-methods study is a follow up to a quantitative pilot study into the efficacy of using a mnemonic technique known as the Keyword Method in an English Communication class at a university in Japan conducted two years earlier. The original study using pre- and post-tests found that instruction in the Keyword Method resulted in a statistically significant improvement in vocabulary that was not likely to have occurred by chance, t(68) = 17.88, p < .00001. The current study used a questionnaire which included ten Likert-scale statements, and an open-ended comments section that was analysed using open coding. The research was designed to explore student perceptions of using the Keyword Method in a foreignlanguage classroom environment with the hope of informing pedagogical decisions and improving learner outcomes. Responses were overwhelmingly positive and seem to support the use of the mnemonic strategy in a classroom environment.journal articl