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Statistics-Based Measuring Point Selection for Monitoring the Thermal Deformation of a Workpiece in End-Milling
Get PDFThe deformation of the thermal workpiece in the end-milling process has a significant effect on the accuracy of machining. In-process direct measurement of workpiece deformation is difficult because process disturbances occur during machining. On the other hand, local temperatures of the workpiece can be easily and accurately measured using common measuring methods. This study aims to develop a monitoring method for workpiece deformations. A sensor-configured thermal simulation is proposed by combining local temperature measurements with thermal simulations to estimate the thermal states of the workpiece in small-lot production. Furthermore, an empirical modeling method is introduced to estimate the workpiece deformation from measured temperatures, thereby accelerating process time. A reliable estimation requires the selection of appropriate measuring points. Using multiple linear regression (MLR), a statistics-based selection method is proposed to establish a relationship between thermal deformation and temperatures of measuring points in various machining situations. During the end-milling process, the predicted time-series of deformations at the machining point and temperatures of the measuring points are regarded as output variables and input variables, respectively, in the finite element method (FEM)-based thermal simulation. The number of measuring points is determined by evaluating Akaike information criterion (AIC), and effective measuring points are selected using the p-value index. The proposed systematic construction method is evaluated using simulation-based case studies. The constructed temperature-based model for measuring workpiece deformation corresponded well to the FEM simulation. Therefore, the constructed model can represent workpiece deformation with the minimum number of measuring points.journal articl
Fundamental Study on Shear Strength and Repair Effect for Reinforced Concrete Beam with Frost-damaged Side Surface
Get PDF本研究では,鉄筋コンクリート(RC)梁を対象に,凍結融解作用による劣化程度と深度,補修の有無がせん断耐力に及ぼす影響を検証した.液体窒素により凍結融解作用を与え,段階的にRC梁の片方の側面を劣化させ,3点載荷試験を実施した.片側側面表層の相対動弾性係数が60%近くまで劣化すると,せん断強度が7.5%程度低下したが,ポリマーセメントモルタルで補修することで,せん断強度が回復した.また既往のトラス・アーチ機構に基づくせん断強度式により,劣化した梁,さらに補修した梁試験体の実験値を適切に評価できた.journal articl
An Evolutional Topology Optimization of Electric Machines for Local Shape Modification and Visualization of Sensitivity Distribution Based on CMA-ES
Get PDFThis paper presents an evolutional topology optimization of electric machines, which works like gradient based local search methods, based on the covariance matrix adaptation evolution strategy (CMA ES). The present method enables to improve the performance of initial machine shapes without computing the deviation of the objectives. Moreover, for the resultant shapes obtained by the present topology optimization method, this paper also presents a sensitivity analysis method based on the nor mal distribution which is used to seek for solutions in CMA ES. Using the present sensitivity analysis method, important parts which contribute to improve a machine characteristic can be visualized. The two present methods are applied to the optimization problem of a synchronous reluctance motor. It is shown that initial rotor shapes defined by designers can effectively be modified using the present optimization method. Moreover, it is also shown that the sensitivity distributions with respect to some machine characteristics are visualized by the present method. In addition, each machine characteristic is respectively improved by modifying the machine shape according to the respective sensitivities.journal articl
AI in SAGIN: Building Deep Learning Service-Oriented Space-Air-Ground Integrated Networks
Get PDFIn next-generation mobile communications, spaceair-
ground integrated networks (SAGINs) is an emerging infrastructure
in future wireless access networks. Since artificial
intelligence (AI) applications become more and more important,
it is essential to build a deep learning service-oriented SAGINs.
In this article, we present a hierarchical intelligent computing
structure focusing on processing deep learning tasks in future
SAGINs. An optimization strategy is also proposed to improve the
quality-of-service (QoS) of deep learning tasks in the proposed
structure. We test our work in small testbed and simulations.
The evaluation results show that the proposed work outperforms
other offloading strategies in a SAGIN environment.journal articl
波浪による転動石の鋼製桟橋への衝突の再現実験
Get PDF小型船舶の係留施設として整備中のコンクリート底板を有する鋼製桟橋において，鋼管に取り付けられたゴム製防護工が，波浪による転動石の衝突により破損した．本研究では，現地の消波堤および桟橋を縮尺1/30で再現し，不規則波実験を行って，桟橋周辺に存在していた直径20～40cmの粗石の耐波安定性を明らかにした．次に縮尺1/10の大型実験を行って，不規則波群中の最高波の流れ場を段波により再現し，粗石を模擬した球体模型の直径を変化さえて，安定限界流速を求めた．その上で，安定限界を上回る流れが作用した場合の球体模型の移動速度を求めた．さらに円柱部材に組み込んだ分力計により，球体模型の衝突力を測定した．その結果，防護工の被災時と設計波の2つの波浪条件に対して，粗石の直径と衝突力の関係を示した.A steel platform with concrete bottom plates has been constructed as a mooring facility for small boats in a fishing port. Rubber protectors covering the steel piles were damaged due to the collision of rubble stones activated by the wave action during under construction stage. This study clarified the moving patterns of rubble stones in front of the steel platform by random wave experiments at a scale of 1/30 for the wave and tidal conditions when the damage happened. In addition, the characteristics of moving speed of the sphere type model for the maximum wave condition were examined by dam-break wave experiments at a scale of 1/10. The relationship between the collision force and the flow speed was shown based on the momentum conservation law. As a result, it was shown that the collision force was peak for the typical diameter conditions.journal articl
Stability of Zirconium-Substituted Face-Centered Cubic Yttrium Hydride
Get PDFThe stability of hydrogen in a zirconium (Zr)-substituted face-centered cubic (FCC) yttrium (Y) hydride (ZSY) phase was investigated experimentally and theoretically. Two possible sites for hydrogen atoms exist in the FCC structure, namely the T- and O-sites, where hydrogen is present at the center of the tetrahedron and the octahedron composed of Y and/or Zr metals. The P-C isotherms revealed that the hydrogen content per metal (H/M) with 33% Zr-substituted YH3−δ was 2.2-2.3, which was lower than the expected value calculated from the starting composition of YH3-33%ZrH2 (Y0.67Zr0.33H2.67) and 2H MAS. An NMR study revealed that the deuterium (hydrogen) at the O-site in ZSY mainly reacted during the deuterium (hydrogen) desorption/ absorption process. Based on a theoretical analysis, when at least two of the six vertices of the octahedron were composed of Zr, its center, i.e., H at the O-site, became unstable. Such unstable O-sites, where more than two Zr is coordinated, nonlinearly increased with an increasing in the Zr content, and when the Zr content was over 50%, almost all of the O-sites were unstable. The theoretical discussion supported the experimental results, and the Zr substitution was confirmed to reduce the stability of the H at the O-site in the FCC YH3 significantly.journal articl
人口減少を克服する都市公園の役割に関する研究－都市公園ビジネスの観点から－
Get PDF室蘭工業大学Muroran Institute of Technology博士（工学）application/pdf人口減少が進む我が国では，地方の雇用創出や移住の推進，出生数の向上等を政策分野とする地方創生が重要な政策課題である。これは都市公園でも同様である。これからの都市公園は，都市・地域・市民のために都市公園の多機能性を一層発揮することが求められており，この多機能性の一つに地方創生が含まれるためである。また，都市公園の多機能性を一層発揮するためには，民間事業者との連携が鍵となっており，ビジネス色の強い民間事業者との連携（本研究では「都市公園ビジネス」という）を加速させるために公募設置管理許可制度（Park-PFI）が創設されている。そこで，本研究は，都市公園ビジネスを通じた人口減少を克服する都市公園の具体的な役割を明らかにすることを目的として，まず1つめとして，都市公園における官民連携の実態把握を行い，2つめとして都市公園ビジネスに対する民間事業者の意識調査を行い，3つめとして都市公園ビジネスに対する地方公共団体の意識調査を行った。1つめの研究は，官民連携の実態把握であった。近年，全国で導入が進んでいる都市公園でのサウンディング型市場調査や公募の事例を幅広く収集して，都市公園の種別，地域分類，時系列変化，公募目的，民間事業者の属性等を明らかにするとともに，地方創生との関連性を明らかにした。2つめの研究は，民間事業者の意識調査であった。都市公園ビジネスに関心を持っている全国の民間事業者に対するアンケート調査を行い，都市公園ビジネスに対する「動機」，「条件」，「タイプ」の因子分析と相関分析を通じて，都市公園ビジネスの特性と人口減少克服との関連性を明らかにした。3つめの研究は，地方公共団体の意識調査であった。全国の地方公共団体に対するアンケート調査を行い，都市公園ビジネスに対する期待効果，期待するビジネスタイプ，課題，民間事業者に期待する能力等を把握するとともに，都市と地方別の回答傾向の比較を通じて，人口減少克服との関連性を明らかにした。最後に，これらの結果を踏まえて都市公園には，「多様なビジネス創出による人口減少に貢献する役割」と「民間事業者の能力向上の機会を提供する役割」があることを総合考察した。以上より，本論文は，人口減少を克服する都市公園の新たな役割の具体像を提示するものである。この結果は，人口減少時代の都市公園の存在価値を高める上で，有用な成果と考える。In Japan, where the population is declining, regional creation is an important policy issue, with the creation of employment, promotion of migration, and increase in the number of births in rural areas as policy areas. This is also true for Urban parks. Urban parks are required to demonstrate their multiple functions for the benefit of cities, regions and citizens, and one of these multiple functions include the regional creation. Cooperation with the private enterprise is the key to make the multiple functions of urban parks more effective. For this reason, Park-PFI has been established to accelerate cooperation with private enterprise with a strong business orientation (in this paper, we call it "businesses utilizing urban parks"). Therefore, I conducted three studies with the aim of clarifying the specific role of urban parks in overcoming population decline through the “businesses utilizing urban parks”. The first was to understand the actual situation of public-private cooperation in urban parks, the second was to survey the attitudes of private enterprises toward the "businesses utilizing urban parks", and finally the third was to survey the attitudes of local governments toward the "businesses utilizing urban parks". The first study was to understand the actual situation of public-private cooperation. I collected a wide range of examples of sounding market research and public call for proposal in urban parks, which have been introduced nationwide in recent years, and clarified the types of urban parks, regional classifications, changes in time series, purposes of public solicitation, and attributes of private businesses, as well as the relevance to local development. The second study was a survey on the attitudes of private enterprises. I conducted a questionnaire survey of private enterprises nationwide who are interested in the urban park business. Through factor analysis and correlation analysis of "motivation," "conditions," and "type" of urban park business, I clarified the relationship between the characteristics of the "businesses utilizing urban parks" and overcoming population decline. The third study was a survey on the attitudes of local governments. I conducted a questionnaire survey of local governments across Japan to understand the expected effects of the "businesses utilizing urban parks", expected business types, issues, and expected capabilities of private businesses. Finally, based on these results, I found that there is a role for contributing to population decline through diverse business creation and a role for providing opportunities for private sector operators to improve their capacity. In conclusion, this paper presents a new role of urban parks in overcoming population decline. The results of this study are useful in enhancing the value of urban parks in the era of population decline.doctoral thesi
New aspect of photophysics of 7,7,8,8-tetracyanoquinodimethane and its solvated complexes: intra- vs. inter-molecular charge-transfer
Get PDFapplication/pdfWe performed laser-induced fluorescence (LIF) spectroscopy of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and its solvated complexes with acetonitrile (ACN) and benzene (Bz), under the jet-cooled gas-phase condition. We also carried out fluorescence and its time profile measurements in TCNQ/Bz/hexane solution to compare with the gas-phase results. The LIF excitation spectrum of the S-1 (pi pi*)-S-0 electronic transition of TCNQ monomer exhibited unusual vibronic structure with the maximum intensity at similar to 3000 cm(-1) above the band origin. In addition, the fluorescence lifetime is more than 100 times longer than that in hexane solution with most of the bands showing double exponential decay. The unusual feature of the vibronic bands is intrinsic and not due to the presence of other species, as confirmed by UV-UV hole-burning (HB) spectroscopy. These unusual features of S-1 are thought to be due to the coupling with the S-2 state, where S-2 was revealed to have intramolecular charge-transfer (ICT) character. The S-1-S-0 transition of the TCNQ-ACN complex exhibited sharp vibronic bands which are red-shifted by 120 cm(-1) from those of the monomer, indicating van der Waals (vdW) interaction between them; however, the fluorescence lifetime was drastically shortened. In contrast, the TCNQ-Bz complex gave a broad electronic spectrum. The study of the fluorescence and its time profile in TCNQ/Bz/hexane solution clearly shows the formation of the CT complex between TCNQ and Bz. Based on the experimental results and density functional theory (DFT) calculations, we propose that in the TCNQ monomer and TCNQ-ACN complex the S-1 (pi pi*) state is coupled to the intramolecular CT state, while the S-1 state of TCNQ in the TCNQ-Bz complex is more strongly coupled to the intermolecular CT state.journal articl
Non-Enzymatic Desymmetrization Reactions in Aqueous Media
Get PDFapplication/pdfSymmetric organic compounds are generally obtained inexpensively, and therefore they can be attractive building blocks for the total synthesis of various pharmaceuticals and natural products. The drawback is that discriminating the identical functional groups in the symmetric compounds is difficult. Water is the most environmentally benign and inexpensive solvent. However, successful organic reactions in water are rather limited due to the hydrophobicity of organic compounds in general. Therefore, desymmetrization reactions in aqueous media are expected to offer versatile strategies for the synthesis of a variety of significant organic compounds. This review focuses on the recent progress of desymmetrization reactions of symmetric organic compounds in aqueous media without utilizing enzymes.journal articl
On-Machine Estimation of Workholding State for Thin-Walled Parts
Get PDFapplication/pdfThe objective of this research is to investigate an on-machine estimation method to achieve efficient and fast estimation of the fixturing force and workpiece deformation. The estimation enables us to visualize 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 were 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.journal articl