Memoirs of the Muroran Institute of Technology No. 73

application/pdf個々の収録アイテムdepartmental bulletin pape

ゴム緩衝材を設置したFRPシート接着曲げ補強RC梁の耐衝撃挙動に関する実験的研究

室蘭工業大学Muroran Institute of Technology博士（工学）近年，既設 RC 構造物の耐衝撃性向上法の１つとして，軽量で施工性に優れる FRP 材料を用いた補強方法が多く採用されている．耐衝撃用途構造部材の補強問題の場合には，載荷点部に緩衝材を設置して衝撃力の緩和や分散，載荷点部における損傷の低減を図ることが肝要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，載荷点部にゴム緩衝材を設置した場合における FRP シート接着曲げ補強 RC 部材の耐衝撃挙動を明らかにすることを目的に，アラミド繊維シート（AFRP）接着曲げ補強 RC 梁に関する重錘落下衝撃荷重載荷実験を実施した．本論文の構成は，以下の通りである． 第１章は序論であり，本研究の背景や既往の研究，および本研究の目的について述べている． 第２章では，本研究で実施した RC 梁に関する静荷重および重錘落下衝撃荷重載荷実験の概要について述べている． 第３章では，本研究で用いたゴム緩衝材単体に関する静的挙動性状について述べている． 第４章では，AFRP シート接着曲げ補強 RC 梁に関する静的耐荷性状について述べている．検討の結果，本研究で採用した RC 梁の破壊形式は，シート補強量の大小によって「曲げ圧壊型」と「剥離破壊型」に分類されることを確認している． 第５章では，ゴム緩衝材を設置した無補強 RC 梁に関する重錘落下衝撃荷重載荷実験について述べている．検討の結果，ゴム緩衝材を設置することによって載荷点部の損傷や斜めひび割れの発生が抑制されること，最大重錘衝撃力が著しく低減されるものの，支点反力および変位波形はゴム緩衝材設置の有無にかかわらず類似する傾向を示すことを明らかにしている． 第６章では，「曲げ圧壊型」AFRP シート接着曲げ補強 RC 梁の耐衝撃挙動について述べている．検討の結果，ゴム緩衝材設置の有無によらずシート破断によって終局に至ること を明らかにしている． 第７章では，「剥離破壊型」AFRP シート接着曲げ補強 RC 梁の耐衝撃挙動について述べている．検討の結果，ゴム緩衝材を設置しない場合にはシート剥離，設置する場合にはシート破断によって終局に至ることを明らかにしている． 第８章では，AFRP シート接着曲げ補強 RC 梁の耐衝撃性について述べている．検討の結果，本研究の範囲では，曲げ圧壊型と剥離破壊型の RC 梁は共に類似の耐衝撃性を有すること，ゴム緩衝材を設置することによって耐衝撃性は向上すること等を明らかにしている． 第９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．Recently, FRP bonding method together with the steel-plate jacketing method and the concrete thickness increasing method have been better applied to retrofit and/or strengthen existing concrete infrastructures. In the case of strengthening the structures using an FRP sheet, it is essential to effectively decrease the high intensity of the impact force, to disperse the force, and to restrain the loading surface from suffering damage. From this point of view, in this paper, in the case of placing a cushion rubber as the absorbing material, in order to investigate the impact resistance behavior of the RC beams strengthened in flexure with bonding FRP sheet to the tension-side surface, the drop-weight impact loading tests for the beams reinforced with Aramid FRP (AFRP) sheet were conducted varying drop height of the 300 kg steel weight, the sheet volume, and with/without placing the cushion rubber. The results obtain from this study are as follows: 1) damage to the impacted surface and development of the flexural cracks from the upper fiber and the diagonal cracks can be drastically restrained by placing the rubber; 2) the primary peak impact force can be decreased by less than one-fifth and the high frequency components including in the impact force can be effectively filtered; 3) however, reduction ratios of the maximum and residual deflections were only around 10% and 20%, respectively, because of impulse of the impact force being approximately similar irrespective of with/without placing the rubber; 4) in the case of the concrete crushing intermediate crack (IC) debonding type of RC beams statically, the beams reached the ultimate state due to the sheet rupturing irrespective of with/without placing the rubber; 5) in the case of the premature IC debonding type of RC beams, the beams reached the ultimate state due to the sheet debonding without placing the rubber, but due to the sheet rupturing with placing the rubber; and 6) the impact resistance capacity of the beams may be improved due to placing the rubber.doctoral thesi

ユーザ中心の無線システムに向けて：カスタマイズと持続可能性のための再構成可能なインテリジェント表面の最適化

室蘭工業大学Muroran Institute of Technology博士（工学）Reconfigurable intelligent surfaces (RISs) have emerged as a promising technology for future wireless communication systems due to their passive meta-elements, slim design, high integration, cost-effectiveness, and ease of deployment. However, optimizing beamforming at RISs, transmission power at access points (APs), deployment locations of multiple RISs, and association relationships between RISs and IoT devices are crucial for various RIS assisted wireless communication networks. Therefore, this dissertation presents effective solutions to maximize the achievable rates, enhance the coverage probability, minimize power consumption, and optimize the quality of experience (QoE). In this dissertation, four major tasks are proposed on the various multi-RIS-assisted wireless communication scenarios. The first task investigates the influence of multiple RIS on the average achievable rate in indoor communication wireless networks. The second task focuses on exploring the relationships between coverage probability and deployment locations of multiple RIS in outdoor scenarios to maximize coverage while satisfying the network cost constraint. Moreover, the second task introduces a method based on approximate cell decomposition to calculate coverage probability quantitatively. The third task is to optimize power consumption, which consists of exploring the association relationships and minimizing the overall power consumption. Finally, the last task investigates the RIS deployed in the wireless VR THz communication systems to maximize the QoE by jointly optimizing the beamforming vectors at multiple RISs, the transmit power of AP, and the rendering capacity allocation among VR users. To solve the issue, the issue is decomposed into two stages: stage-1 aims to minimize BER and maximize the data rate, while stage-2 aims to maximize rendering capacity among virtual objects.doctoral thesi

Creating a Framework for Encouraging Self-Regulated Learning: Applying Nudge Theory in Japanese Reading Classes

The purpose of this study was to investigate the following two key aspects within the context of Japanese reading classes for international students at a Japanese national university: i. Support for Japanese language learners to acquire academic reading skills, ii. Encouraging Japanese language learners' Self-Regulated Learning (SRL) in Japanese reading classes. In view of this, the following practices were specifically carried out: i. Creating a framework for Japanese reading classes by applying the nudge theory to foster Japanese language learners’ SRL, ii. Elucidating the phases of SRL in Japanese language learning through classwork, thereby nudging students to enhance their metacognitive awareness of SRL phases for Japanese language learning. The findings of this study indicate that the framework for Japanese reading classes that apply the nudge theory is effective in encouraging Japanese language learners' SRL in this case. However, further research is necessary on the formation process of SRL in individual learners.departmental bulletin pape

大型鋳鋼品におけるポロシティと疲労強度との相関

室蘭工業大学Muroran Institute of Technology博士（工学）プレス部材，圧延機用ロールスタンドなど数 100 トンを超える鋳鋼品は大型鋳鋼品と言われる．これらは，使用環境が過酷であることから高い靭性と繰り返し荷重に長時間耐えうることができる高い疲労限度を有し，溶接性に優れ高強度であることが求められる．しかし，鋳鋼品では不可避的に鋳造欠陥（ポロシティ）や割れが発生する．本研究では，鋳鋼品における鋳造欠陥と疲労強度との相関について解明し，鋳造方案立案や疲労限度を推定することを目的とした． 鋳鋼品において凝固解析技術を駆使し，鋳造欠陥（ポロシティや割れ）を精度よく予測することは，健全な鋳物を製造するため，欠かすことができない技術である．本論文では凝固解析における各種材料物性値を検討し，連続測温により得られた冷却曲線より最適な物性値を設定することができた．また，疲労限度を顕著に低下させる凝固割れを予測する技術も必要不可欠である．本実験結果より鋳鋼における割れ発生メカニズムを解明し，割れ感受性指標と割れとの相関を得た．得られた結果から凝固解析に反映することで複雑形状品でも凝固割れを予測することが可能となった． また，極値統計法，X 線 CT 装置を活用した疲労限度予測について検討した．NiCrMo鋼に発生するポロシティが疲労限度に与える影響について√を用いて調査し，疲労限度予測式を推定することができた．そして，欠陥評価に産業用 X 線 CT システム及びマイクロ X 線 CT システムを使用し，一般的な大型鋳鋼品に用いられる SCW480 鋼において鋳鋼品内部に発生する欠陥と疲労限度の関係を調査した．その結果より応力勾配を考慮した予測式を導出し，X 線 CT を用い試験材内部の欠陥面積，中立線からの距離を測定することで疲労限度予測式を導出した．また、組織が異なる各種供試材においても疲労限度予測式から算出した値は誤差 10％以内で疲労限度を予測可能であることを確認した． 大型鋳鋼品において凝固解析によるポロシティ予測と疲労限度予測式を導出したことから実機品におけるポロシティ予測と疲労限予測を実施した．凝固解析及び疲労限度予測を実施し，製品品質を評価した．凝固解析では健全度予測を満足する鋳造方案を立案し可能な限り健全な鋳鋼品を製造する．凝固割れ解析を実施し，最大応力部に割れが発生しないよう製造する．応力解析を実施することで疲労限度を予測する．以上の手法，手順により製造することが健全な鋳鋼品を製造する上で最重要であることが分かった．今後，本製造方法を適用し製造すべきである．Steel castings that weigh more than several hundred tons, such as press components and roll stands for rolling mills, are called large castings. Because of the harsh operating environment, these products must have high toughness, a high fatigue limit that can withstand repeated loading for a long period of time, and high strength with excellent weldability. However, cast steel products inevitably suffer from casting defects (porosity) and cracking. The purpose of this study is to elucidate the correlation between casting defects and fatigue strength of cast steel products and to estimate the casting method and fatigue limit. The accurate prediction of casting defects using solidification analysis technology is an indispensable technique for the production of sound castings. In this paper, various material properties in solidification analysis are investigated, and the optimum property values are determined from cooling curves obtained by continuous temperature measurement. It is also essential to have a technique to predict solidification cracking, which significantly reduces the fatigue limit. From the experimental results, the mechanism of cracking in cast steel was clarified, and a correlation between cracking susceptibility indices and cracking was obtained. The obtained results can be reflected in solidification analysis to predict solidification cracking even in complex-shaped products. The influence of porosity generated in NiCrMo steel on fatigue limit was investigated using extreme value statistical method and X-ray CT system, and the fatigue limit prediction equation was estimated. In addition, the relationship between the fatigue limit and the defects inside the castings of SCW480 steel, which is generally used for large castings, was investigated by using an industrial X-ray CT system and a micro X-ray CT system for defect evaluation. From the results, a prediction equation considering the stress gradient was derived, and the fatigue limit prediction equation was derived by measuring the defect area and the distance from the neutral line inside the specimen using the X-ray CT system. It was confirmed that the fatigue limit could be predicted within an error of 10% for various specimens with different microstructures. Porosity and fatigue limit prediction equations were derived for large cast steel products by solidification analysis. The product quality was evaluated by solidification analysis and fatigue limit prediction. In the solidification analysis, a casting plan that satisfies the soundness prediction is developed to produce as sound a cast steel product as possible. Solidification cracking analysis is conducted to ensure that cracking does not occur in the area of maximum stress. To predict the fatigue limit by conducting stress analysis. It was found that the above methods and procedures are the most important for producing sound cast steel products. This manufacturing method should be applied in the future.doctoral thesi

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。

This 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

RESEARCH OF SPATIAL IMAGING TECHNOLOGY ON SUPPORTS OF IMPROVEMENT AND MANAGEMENT FOR MEDIUM AND SMALL RIVERS

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

表紙・奥付

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Phonology of the Diphthongs in Modern Icelandic− Particular Focus on the Interpretation of their ‘Length’ −

A 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

Time Adverbs Indicating Duration and Progress in Ainu Language from a Japanese Perspective

本稿ではアイヌ語の「時間関係の副詞」を、事態存続の時間量を表すもの、時間の中での事態の進展を表すもの、起動への時間量を表すものの三種類に分け、それらの意味と構文の特徴について記述した。事態存続の時間量を表す時間副詞は、形式上バリエーションが多く、構文上、動作動詞と共起する場合はその動作の持続時間を、変化動詞と共起する場合はその変化した結果の持続時間を表す。時間の中での事態の進展を表す時間副詞には、「uweepakta（だんだん）」、「usimne（日一日）」などがある。これらの時間副詞は変化動詞と共起する場合、変化の漸進的進展を表し、動作動詞と共起する場合は繰り返しの意味で解釈されることがあり、事態の進展性を示す。起動への時間量を表す時間副詞には、アイヌ語で「nisapno（急に）」、「ekuskonna（突然）」、「oykesne（しまいに）」などがあり、これらは各々異なる時間の長さを示しながらも、事態の起動や取り掛かりまでの所要時間量を表す。journal articl