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Shear strengths of joints with roughened concrete surfaces and post-installed dowel bars subjected to normal and shear stresses for seismically retrofitted structures
Get PDFWhen reinforced concrete ( structures are seismically retrofitted, new members are
connected via joint s with roughened surfaces and post installed dowel bars. For retrofit ted RC build-
ings , roughened surface s are often manufactured using vibration hammer s . However, investigations
on the shear strength s of the joints subjected to shear and tensile normal stress es are limited. In this
study, these joints called hybrid joints, were subjected to shear loading . The test parameters we r e
the normal stress dowel bar diameter d d and roughened c oncrete area ratio r rc . The normal stress
was set to have a compressive stress σ 0 of 0.48 N/mm 2 and a ratio s r N o f tensile stress to yield
strength of 0.00, 0.33 and 0.66. In addition, dowel bars with d d = 13, 16 , and 19 mm were used. The
target r rc values were 0.1 0.2 and 0.3. Bearing failure of the roughened surface was observed as a
result of the test. The shear strength decreased with increasing r N and decreasing r rc . Subsequently ,
an expression for the shear strength of a roughened surfac e wa s proposed. In this expression, the
shape of an uneven surface was regarded as a cone. To estimate the shear strengt h s of the hybrid
joint s , the shear force from the previous dowel model was added to the proposed expression. Finally,
the values obtained us ing th e calculation method were compared with the test results . It was demon-
strated that the proposed expression could r easonably estimate the test results , with a correlation
coefficient of 0.93 . In addition, for structural design s , the proposed expression should be multiplied
times 0. 7 to e stimate the lower limit of the test results.journal articl
薄肉部品の精密加工のための工作物保持状態の機上推定
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdf薄肉部品は，高度な比強度を実現する構造として現代の製造業で広く使用されています．しかしながら，別の観点から見ると，これらの部品は構造が複雑で，剛性が低く，高精度な加工が必要になります．機械加工中においては，剛性の低い構造特性のため，実際の工作物保持の実施工程と把持具の選択により，薄肉部品の変形は大きく影響されます．さらに，ほとんどの工作物把持工程は手動操作として実行されるため，プロセスのばらつきが大きくなります．これらの変動する固定プロセスは，長い間加工精度を低下させてきました．この研究の目的は，固定力と工作物の変形を効率的かつ迅速に推定するためのオンマシン推定方法を調査することです．この推定により，工作物保持状態の視覚化が可能になり，薄肉部品の加工精度が向上します．本研究では，工作物把持シミュレーションと局所的に測定されたひずみを組み合わせた工作物把持状態の体系的な推定方法を提案し，その妥当性を評価します．提案されたオンマシン推定方法は，さまざまな工作物保持条件（把持シーケンスと固定力）で評価されます．把持された状態での薄肉工作物の推定固定力と工作物の変形を，実験結果と比較した．実験結果との比較から，提案手法は固定力不足や過度の変形などの不適切な工作物保持状態を検出する可能性があることが明らかになりました．この論文では，複数の基盤技術を用いて機械加工プロセスにおける薄肉部品のワーク保持状態を推定するシステムを構築しました．本編の構成は以下のとおりです．まず，本研究の背景として，最近の生産動向をまととめました．現代の製造業に適用される薄肉部品の役割，薄肉工作物加工の動向，薄肉工作物の重要性について整理します．さらに，工作物を把持した状況における工作物把持状態の推定，測定技術の開発，FEM分析，および測定とシミュレーションの組み合わせに関する関連研究の調査結果を示します．次に，本研究の目的を具体的に達成するために設定された4つのステップについて説明します．（1）オンマシン推定の実現可能性の検証（2）工作物固定力の推定（3）工作物把持シーケンスの影響評価（4）測定点の選択手法の構築 そして，オンマシン推定の枠組みを提案します．プロセス変数の考察に基づいて，状態推定のための最適化プロセス，工作物把持シミュレーションの枠組み，複雑形状工作物に対する把持状態推定の流れ，および測定可能点の評価指標の有効性について検討した結果を示します．この研究は，薄肉部品の工作物把持状態推定のための効果的なシステムを構築するためにこれらの方法を連携させる手法を提案しました．さらに，研究目的を達成するための4つのステップに基づいて，提案を検証するために行った，評価実験について紹介します．評価実験の結果から，提案された工作物把持状態の推定方法は，さまざまな工作物把持状況において，工作物把持状態を推定し視覚化することができることが明らかになりました．最後に，本論文の結論について述べます．Due to the higher structure efficiency and lightweight characteristic, thin-walled parts are widely used in the modern manufacturing industry. However, from another point of view, these parts are complex in structure, have weak stiffness, and high precision demand. During the machining process, because of low rigidity structural characteristics, actual workholding process and fixture selection are heavily affected by the deformation of thin-walled parts. Moreover, most of the fixturing process is executed as manual operations, which generate large process variations. These fluctuated fixturing processes have deteriorated machining accuracy for a long time. The objective of this research is to investigate an on-machine estimation method to achieve an efficient and fast estimation of the fixturing force and workpiece deformation. The estimation enables visualization of workholding states and improves machining accuracies of thin-walled parts. In this research, a systematic estimation method of workholding states which combines fixturing simulation and locally measured strain is proposed and evaluated. The proposed on-machine estimation method is evaluated in different workholding conditions (clamping sequences and fixturing forces). Estimated fixturing force and workpiece deformation for a clamped thin-walled workpiece was compared to the results from the engineering experiments. From the comparison, it becomes clear that the proposed method has the feasibility to detect improper workholding states such as insufficient fixturing force or excessive deformation. In this thesis, several methods are used to build a system to estimate the workholding state of thin-walled parts in the machining process. The main story is described as follows. Firstly, trends of recent production are summarized as a background of this research. Roles of thin-walled parts which apply in the modern manufacturing industry, trends of thin-walled workpiece machining, and the importance of thin-walled workpieces are introduced. Moreover, related researches about workholding state estimation in workholding situations, measurement technology development, FEM analysis, and a combination of measurement and simulation are surveyed. Secondly, to concretely explain the overall objective, the whole research process is illustrated to follow four steps: (1) Feasibility verification of On-machine estimation (2) Fixturing force estimation (3) Effect of clamping sequence (4) Measurement points selection Thirdly, a framework for on-machine estimation is proposed. Based on considerations of process variables, a concept of the iteration optimization process, workholding simulation framework, estimation flow of complex workholding state, and evaluation criterion of measurable points are explained. This research presents these methods to build an effective system of thin-walled parts workholding estimation. Fourthly, several case studies are set to verify our proposal based on the four steps of the objective paragraph. From the results of case studies, the proposed estimation method of workholding state can visualize the fixturing states in various workholding situation. Lastly, the conclusion of the dissertation is described.doctoral thesi
Layer Based Firewall Application for Detection and Mitigation of Flooding Attack on SDN Network
Get PDFSoftware-Defined Networking (SDN) is an emerging Network technology that can augment the data plane with control plane by using programming technique. However, there are a numbers of security challenges which are required to address to achieve secured communication. Flooding attack is one of the most common threats on the internet for the last decades which is becoming the challenging issues in SDN networks too. To address these issues, we proposed a novel firewall application developed based on the multiple stages of packets filtering technique to provide flooding attack prevention system and layer-based packets detection system. In this research, we are using two main stages to detect the flooding attack and mitigate the flooding packets. The first stage is to identify the attacks and, the second stage is to identify the attacker’s information and act them based on layer-based packet header entity. The system contains two security entities to identify the flooding attacks, one is by measuring the packet size, and the other is by counting the packets flow. We used the details of packets flow to control over the flow and to identify the attacks being occurred or not. Along with, to identify the attacker’s information, we used layers (layer 2 to layer 4) based packet header entities by using multi-table architecture. The proposed solution was tested for different attack scenarios and successfully reduced the flow of volume-based bulk-size flooding attack and infinite packets flooding attack in SDN network.journal articl
The origin of the highly crystallized face-centered cubic YH3 high-pressure phase when quenched to ambient condition
Get PDFThe origin of the face-centered cubic (FCC) structure in yttrium trihydride stabilized (or quenched) at ambient pressure was investigated using transmission electron microscopy (TEM) and in situ synchrotron x-ray diffraction (XRD) measurements under high pressures in the gigapascal range. Although the FCC-YH3 high-pressure phase is normally unstable at ambient pressure,in this study, we found that the FCC-YH3 phase, with high crystallinity, could be obtained via sintering at 1373 K for 24 h under 6 GPa, and subsequent quenching at a rate greater than 1000 K/min. The XRD profile of the FCC-YH3 phase showed sharp peak patterns, i.e., it had a high crystallinity; however, the TEM observations revealed that the surfaces of the particles were significantly disordered. It was observed that these surface defects played an important role in keeping the FCC-YH3 high-pressure phase present at the ambient pressure. In situ XRD measurements during highpressure and temperature processing confirmed that the YH3 phase structure had completely transformed from HCP to FCC at 1173 K and 9 GPa; however, the amount of HCP-YH3 ambient pressure phase increased continuously during cooling and depressurization. The sample cooling rate during in situ measurements was 90 K/min, which was more than ten times slower than that in the ex situ experiments. Since the defects introduced into the surface of the particles during the slow cooling process were insufficient, a reversal of the HCP-FCC reversible structural change was observed during the depressurization after sintering.journal articl
Efficiency-Aware Dynamic Service Pricing Strategy for Geo-Distributed Fog Computing
Get PDFFog computing provides new ideas for solving big data problems in the Internet of Things (IoT) era. With fog, we can save much time on long-distance transmission, thereby increasing the efficiency of network service.
However, to transform fog computing from a technology to a service, we first need to properly handle the trading relationship between users and service provider in fog.
In this paper, we design an efficiency-aware dynamic service pricing strategy to optimize the payoffs of both users and provider in fog computing.
In the modeling, we design a Stackelberg competition-based model while regarding provider as the market leader, and each individual user as a follower.
Users in this model care about how to obtain the most cost-effective services. And provider pays attention to taking full advantage of the geo-distributed characteristic in setting prices with multiple customers.
In the performance evaluation part, we carry out experiments using real-world datasets to simulate this continuous negotiation process between supply and demand in fog pricing.
The results show that our strategy can solve the dual-objective optimization problem while establishing a stable trading relationship between the two sides.journal articl
Getting a Grip on Direction of Class Improvement Methods from remote learning
Get PDFapplication/pdfDue to the rapid spread of the new Corona infection, face-to-face classes were restricted to remote classes. And the faculty conducted various questionnaires to the students. In response to the questionnaires, the students not only gave obligatory answers, but also responded with what they wanted in a class. In particular, their requests were expressed in their free opinions. In addition to responding to their own problems, they also asked for support to help them achieve their academic goals. Thus, text mining revealed that it is important to respond to students' learning strategies.特集departmental bulletin pape
Amyloid β aggregation induces human brain microvascular endothelial cell death with abnormal actin organization
Get PDFapplication/pdfCerebral amyloid angiopathy (CAA) is a disease in which amyloid β (Aβ) is deposited on the walls of blood vessels in the brain, making those walls brittle and causing cerebral hemorrhage. However, the mechanism underlying its onset is not well understood. The aggregation and accumulation of Aβ cause the occlusion and fragility of blood vessels due to endothelial cell damage, breakdown of the blood-brain barrier, and replacement with elements constituting the blood vessel wall. In this study, we observed the effect of Aβ on human primary brain microvascular endothelial cells (hBMECs) in real-time using quantum dot nanoprobes to elucidate the mechanism of vascular weakening by Aβ. It was observed that Aβ began to aggregate around hBMECs after the start of incubation and that the cells were covered with aggregates. Aβ aggregates firmly anchored the cells on the plate surface, and eventually suppressed cell motility and caused cell death. Furthermore, Aβ aggregation induced the organization of abnormal actin, resulting in a significant increase in intracellular actin dots over 10 μm2. These results suggest that the mechanism by which Aβ forms a fragile vessel wall is as follows: Aβ aggregation around vascular endothelial cells anchors them to the substrate, induces abnormal actin organization, and leads to cell death.journal articl
Prosodic Features of Utterances when Paying Attention to the Function of Murayama Dialect
Get PDF本研究の目的は、非東京方言母方言話者（ 無アクセント） の日本語教師が、音声指導をする際に一助となる指標を提案することである。発話機能に相応しい村山方言、共通語10 種類の発話を資料に、イントネーションの共通点、相違点を分析した結果、村山方言は共通語と比べ、（1 ） 一拍あたりの持続時間長が長い、（ 2）Fo が低く変動幅が狭い、（ 3） 音圧が大きく変動幅が狭い、という特徴があった。これは発話機能別に分析をしても同じであった。しかし、話者の個人的特徴を排除し、発話機能別に再度分析した結果、《挨拶》、《声掛け》、《協力求め》の3 種類は、方言に関わらず韻律的特徴に共通点があったが、《依頼》《詫び》《許可求め》《祝い》《賞賛》の5 種類は、方言による相違があることが分かった。発話機能を意識した会話を指導する際には、これらの共通点、相違点に留意して指導をすることを提案したい。journal articl
Distinctive Fish Names for Stages of Growth in Samoan
Get PDFサモア語における魚の成長段階名称について、その区分の仕方と名称の形成法について分析した。区分の仕方としては、2 段階区分が最も多いが最大で7 段階もの細かい区分をする魚種もあること、複雑な段階区分がある場合には、幼魚段階と成魚段階の間の中間段階の細分化に加えて、成魚段階よりも更に大きく成長した老魚についても細分化がなされる場合があることが指摘された。また、成長段階名の形成法としては、他の成長段階と無関係の独立名称を用いる場合、成魚名の全体または一部の音節が重複されたものを用いて主に若い成長段階の名称を形成する場合、特定の魚種に共通の要素と特定の成長段階に特有の要素とが結合された複合的名称を用いる場合の三種類あることを指摘した。また、今回の分析の結果と先行研究におけるハワイ語の魚の成長段階名称の分析の結果との比較対照も行った。journal articl
On the Trace of Intramoraic Tonal Declination observedin Class 5 Bimoraic Nouns in Tokushima Dialect
Get PDF本稿では、徳島方言における第5 類2 拍名詞のアクセントについて、拍内下降そのものは存在しないが、その痕跡が残っている場合があることを示す。先行研究によると、徳島方言では拍内下降が生じないかまれであるとの記述があったが、本研究で明らかになるのは、(1) 第2 拍の母音を長音化可能であり、下降音調が顕在化できること、(2) 長音化された第2 拍は2 モーラ分の長さを持っており「拍内」下降ではないこと、(3) 助詞を付加されても、第2 拍は長音化かつ下降音調の顕在化が可能である、ということである。journal articl