Muroran-IT Academic Resource Archive
Not a member yet
5947 research outputs found
Sort by
A Topology Optimization of Electromagnetic Devices Based on Kernel Ridge Regression as a Variant of Gaussian Network-based Shape Representation
Get PDFThis paper presents an evolutional topology optimization method for electromagnetic devices based on Kernel Ridge Regression (KRR). As for this method, device shapes are represented through a spatially smooth function, whose output is determined on the basis of KRR. The present method makes it easy to find some structures with alternating air-region, like multi-barriers in synchronous reluctance motor (SynRM). It is shown that the present method is a variant of the shape expression method based on the normalized Gaussian network (NGnet)-based approach. Nevertheless, it is shown from optimization results of magnetic shield and SynRM that the present method can find smooth but more complicated shapes in comparison with the conventional NGnet-based method.journal articl
A novel floating adsorbent for cesium based on Shirasu balloon modified with magnetite and Prussian blue
Get PDFShirasu balloon (SB) is a hollow glassy sphere produced from volcanic deposits by heating that can float up on water owing to its hollow structure. In this study, a novel adsorbent for the removal of cesium ion in water was developed by the modification of the surface of the SBs with magnetite (Mag) and Prussian blue (PB). The developed adsorbent (PB-Mag-SB) was characterized by elemental analysis, X-ray diffraction and Fourier transform-infrared spectrometry and the magnetism of the adsorbent. From these results and the change in color of the adsorbents, the successful modification of the SBs with magnetite and PB was confirmed. The developed adsorbents were added and mixed with the polluted water. After the adsorption, it could float up on the surface of water due to the buoyancy of the balloon and also be collected by a magnet due to the magnetism of the magnetite formed on the surface of the SB. Furthermore, the removal of Cs from water was achieved by binding site of PB immobilized on the Mag-SB. The PB-Mag-SB could selectively adsorb Cs even in the presence of coexisting cations at high concentrations. The adsorbent remained a float on the water surface for at least 24 h, and approximately 99% of the adsorbent could be collected within 5 min using a magnet. The introduction of both floating and magnetism properties to the adsorbent makes it easy and selective to collect the adsorbent after the adsorption of pollutants in water. SB is a natural product with a low environmental impact, therefore, the adsorbent based on SB will contribute to the environmental remediation as a novel material for adsorptionjournal articl
Literature Created by the Uilta from Sakhalin Island (1)
Get PDF本稿ではサハリンの先住民族ウイルタの、特にウイルタ語による《文学》と、その変化についての初歩的な考察を試みる。ウイルタ語に固有の文字はなく、昔話やおとぎ話、歌謡などは従来、口頭で伝承された。このような口承文芸をウイルタの「伝統文学」と呼ぶ。初めての教科書発行により書き言葉が成立した2008 年以降にウイルタ語の母語話者が主力（またはその一部）となってウイルタ語を書き表した出版物は、2023 年12 月現在、筆者が確認できただけでも17 件ある。そのなかには、話者がウイルタ語で創作した作品を含むものや、他言語からウイルタ語に翻訳した作品がみられる。このような創作や翻訳作品は、ウイルタ語を文字で書いて生み出されている点で、語られる「伝統文学」とは区別される。2008 年以降の創作や翻訳作品のなかにウイルタの「新しい文学」の萌芽を認めるかどうか、多角的かつ長期的な視点での考察を要する。現在ウイルタ語を母語とする話者は10 名に満たず、この言語は消滅の危機に瀕しているとされる。だが、ただ消滅を待つのでなく、伝統文学を再評価して広く紹介したり、書き言葉を成立させてウイルタ語の出版物を次々と出し、若い世代の学習機会を増やしたりして、この言語を後世に伝え残そうとしていることにも注目したい。journal articl
Effects of Alkyl Chain Lengths and Isomers of Alcohols on the Phase Behavior of 1-Alkyl-3-methylimidazolium-Based Ionic Liquid + Alcohol Mixtures
Get PDFPhase separation temperatures of alcohol mixtures of imidazolium-based ionic liquid(IL), 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([Cnmim][TFSA]) and 1-alkyl-3-methylimidazolium tetrafluoroborate ([Cnmim][BF4]) have been measured in order to elucidate effects of alkyl-chain lengths and isomers of alcohols on phase behavior of IL+alcohol mixtures. The investigated IL+alcohol mixtures showed a liquid-liquid upper critical solution temperature (UCST) type phase behavior. The phase separation temperatures of IL+alcohol mixtures increased with elongating the alkyl-chain length of alcohol. The phase separation temperatures of IL+butanol mixtures were higher in the order of 2-methyl-1-propanol (i-BuOH) 1-butanol (1-BuOH) > 2-butanol (2-BuOH) > 2-methyl-2-propanol (t-BuOH). On the other hand, the isomerism effects of propanols on the phase separation temperatures were hardly observed. The upper critical solution temperatures Tc obtained from the phase separation temperatures decreased linearly with elongating the alkyl-chain length of ILs.journal articl
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
Get PDF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
A Study of Hybrid Adaptive Evolutionary Algorithm for Multi-objective Optimization
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）進化アルゴリズムは，生物の進化過程からインスパイアを得ており，交叉，変異戦略，自然選択といった進化操作により最適化を実現している。進化計算は，その高い汎用性および頑健性から，伝統的な数学的計画に比べて幅広い問題に対処することができるという特徴を持つ。特に最近では，進化計算における多点探索という特徴を活かした多目的最適化問題への応用研究が大きな注目を集めている。本研究は，多目的最適化のための効果的な進化計算手法として，新規個体生成のためのメカニズムとしてCX（Cross-over）およびED（Estimation of distribution）戦略を組み合わせた新たな手法を開発し，その有用性を検証した。
多目的最適化は，単目的最適化よりも複雑であるため，探索性能を向上させるためには，より体系的かつ適応的な手法が必要となる。本研究では，代表的な多目的最適化のための進化計算手法であるMOEA/D（Multi-Objective Evolutionary Algorithm Based on Decomposition）フレームワークに焦点を当て，そのフレームワークに新たなメカニズムを導入することによる性能改善を試みた。一般的に，進化計算における新規個体生成では，幅広い範囲を対象とする探索と局所的な範囲を対象にする探査をバランスさせることが重要とされているが，事前の取り組みを通じて，単一の演算子のみでは両者を同時に実現することが困難であることが判明した。そのため，本研究では複数の個体生成の戦略を適応的に切り替える方法を実現することで，探索と探査を自動的にバランスさせ，効率的な探索を実現する手法について検討を行った。
本研究で着目したMOEA/Dフレームワークでは，多目的問題を複数の単目的問題に分割し探索を行う。そのため，単目的問題において大域的な探索を指向する戦略と局所的な探索を指向する戦略を組み合わせることで，多目的最適化においても適応的に両方の戦略を切り替える手法を実現することができる。本研究では，この考えに基づきMOEA/D-EFモデルおよびMOEA/D-HHモデルとしてMOEA/Dを効率化した新規手法を提案した。これらのモデルはMOEA/Dフレームワークに適応的に複数の演算子を切り替えるメカニズムを導入することで探索の効率化を実現している。
論文の第二章では，MOEA/Dフレームワーク，CX戦略およびED戦略に基づく進化演算子，多目的最適化問題で使用される2つの性能メトリクスについて検討しており，第三章では，本研究で導入された進化演算子に焦点を当て，IDE，JADE，DE-IDEAL，およびCMAESについて解説している。第四章では，提案するMOEA/D-EFモデルについて説明し，第五章ではEfficiency Inspectionに基づく演算子切り替えメカニズムを組み込んだMOEA/D-HHモデルについて焦点を当て説明している。Evolutionary algorithms draw inspiration from the natural process of biological evolution, encompassing gene encoding, crossover, mutation strategies, and mechanisms of natural selection. Due to their high robustness and self-learning characteristics, evolutionary computing has emerged as an advanced global optimization technique for handling complex problems, proving more effective than traditional mathematical planning. In recent years, research has increasingly focused on utilizing evolutionary computingfor both single and multi-objective optimization problems. Our study specifically concentrates on effectively addressing multi-objective optimization problems, with a particular emphasis on individual generation methods based on the CX (Crossover) and ED (Estimation of Distribution) strategies in evolutionary algorithms.
Multi-objective optimization problems, more intricate than single-objective ones, demand systematic approaches. We direct our attention to the MOEA/D (Multi-Objective Evolutionary Algorithm Based on Decomposition) framework. However, attempting to design new operators or modify classical ones to enhance overall algorithm efficiency revealed that a single operator cannot handle all search scenarios. Operator search capabilities are typically represented by exploration and exploitation methods, and concurrently possessing both capabilities is often challenging. To overcome this issue and enhance algorithmic search efficiency, it is necessary to combine multiple operators with different search characteristics into a hybrid algorithm and introduce an adaptive operator switching mechanism.
Furthermore, the adaptability of operators within the framework is crucial. Many evolutionary operators were initially designed to mimic the evolution in nature and may not be well-suited for multi-objective optimization problems. In this regard, the MOEA/D framework has caught our attention. This framework can decompose multi-objective optimization problems into multiple sub-problems, allowing for the introduction of classical evolutionary operators. Simultaneously, the MOEA/D framework introduces the concept of the neighborhood of sub-problems, enabling information sharing within the neighborhood during the evolutionary process. Considering this unique feature, our primary research goal is to extend classical evolutionary operators to handle multi-objective optimization problems.
To achieve this goal, we conducted detailed research and analysis on advanced evolutionary operators with different search characteristics and strategies. Subsequently, we proposed the MOEA/D-EF model and MOEA/D-HH model, introducing adaptive operator switching mechanisms to align with the MOEA/D framework.
In the second chapter of the paper, we discuss the MOEA/D framework, evolutionary operators based on CX and ED strategies, and two performance metrics widely used in multi-objective optimization problems. The third chapter focuses on the introduced evolutionary operators, including IDE, JADE, DE-IDEAL, and CMA-ES. The fourth chapter introduces the MOEA/D-EF model, while the fifth chapter delves into the MOEA/D-HH model, emphasizing the operator switching mechanism based on efficiency inspection.doctoral thesi
On geodesics of framed surfaces in the Euclidean 3-space
Get PDFWe would like to dene the notion of geodesics for surfaces with singular points.
As surfaces with singular points, we consider framed surfaces. Moreover, as curves
with singular points, we consider framed curves. Then we give a denition of
geodesic as a framed curve of a framed surface. We investigate properties of the
geodesic and give examples.journal articl
Diphenylanthracene-based Amorphous Molecular Fluorophores for Triplet–Triplet Annihilation Upconversion System
Get PDFNovel diphenylanthracene-based amorphous molecular fluorophores have been designed and synthesized. They were found to exhibit fluorescence emission with fairly high quantum efficiencies both in solution, crystalline state, and amorphous state. And finally, triplet–triplet annihilation upconversion emissions have been achieved not only in toluene solutions but also as amorphous solids using present novel fluorophores as acceptors combined with platinum(II) octaethylporphyrin as a donor.journal articl
Comparison of peripersonal space in front and rear spaces
Get PDFThe space immediately around the body, referred to as the peripersonal space (PPS), plays a crucial role in interactions with external objects and in avoiding unsafe situations. This study aimed to investigate whether the size of the PPS changes depending on direction, with a particular focus on the disparity between the front and rear spaces. A vibrotactile stimulus was presented to measure PPS while a task-irrelevant auditory stimulus (probe) approached the participant. In addition, to evaluate the effect of the probe, a baseline condition was used in which only tactile stimuli were presented. The results showed that the auditory facilitation effect of the tactile stimulus was greater in the rear condition than in the front condition. Conversely, the performance on tasks related to auditory distance perception and sound speed estimation did not differ between the two directions, indicating that the difference in the auditory facilitation effect between directions cannot be explained by these factors. These findings indicate that the strength of audio-tactile integration is greater in the rear space compared to the front space, suggesting that the representation of the PPS differed between the front and rear spaces.journal articl