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Static and impact loading tests on through-type steel-post embedded into proto-type rockfall-protection wall in case of coupling between bending and shearing actions
Get PDFIn order to establish a rational design procedure for the anchoring depth of the steel posts for rockfall-protection fences embedded into the rockfall-protection walls, static and drop-weight impact loading tests on prototype through-type posts in case of coupling between bending and shear actions were conducted. The results obtained from this study were as follows: 1) plastic hinge was formed in the post near the upper surface of the wall not only under static loading but also under impact loading; 2) impact force excluding high-frequency components may be able to estimate approximately by using the static perfect-plastic load; 3) impact energy may be entirely absorbed by the post deforming excluding rotation of the wall; and 4) design values obtained from the specification may be in the safety side comparing with the experimental results.journal articl
New Insights of Polarization Beam Splitter Based on Sinusoidally Driven Directional Coupler
Get PDFThispaper studies on polarizationbeamsplitter (PBS) in high-index-contrast waveguides based on sinusoidally driven directional coupler (SDDC), and offers new insights to realize compact and low-loss PBS with high fabrication tolerance. The PBS based on SDDC has advantage that power shift to an adjacent waveguide can be suppressed or totally banned by satisfying coherent destruction of tunneling (CDT) condition. However, in practical implementation, the PBS based on SDDC has trade-off relation between cross-talk of TE-likewave and loss of TM-like one. This paper investigates characteristics of the SDDC numerically, and shows possibility that cross-talk and loss can be suppressed, and small footprint can be achieved by position shift of DC-gap maintaining high fabrication tolerance.journal articl
Changes in mobility amid the COVID-19 pandemic in Sapporo City, Japan: An investigation through the relationship between spatiotemporal population density and urban facilities
Get PDFBy the end of 2021, the Omicron variant of coronavirus disease 2019 had become the dominant cause of a worldwide pandemic crisis. This demands a deeper analysis to support policy makers in creating interventions that not only protect people from the pandemic but also remedy its negative effects on the economy. Thus, this study investigated people’s mobility changes through the relationship between spatiotemporal population density and urban facilities. Results showed that places related to daily services, restaurants, commercial areas, and offices experienced decreased visits, with the highest decline belonging to commercial facilities. Visits to health care and production facilities were stable on weekdays but increased on holidays. Educational institutions’ visits decreased on weekdays but increased on holidays. People’s visits to residential housing and open spaces increased, with the rise in residential housing visits being more substantial. The results also confirmed that policy interventions (e.g., declaration of emergency and upgrade of restriction level) have a great impact on people’s mobility in the short term. The findings would seem to indicate that visit patterns at service and restaurant places decreased least during the pandemic. The analysis outcomes suggest that policy makers should pay more attention to risk perception enhancement as a long-term measure. Furthermore, the study clarified the population density of each facility type in a time series. Improving model performance would be promising for tracking and predicting the spread of future pandemics.journal articl
Shear Resistance of Post-installed Anchors for Freezing Damaged Concrete Surface
Get PDF寒冷地の鉄筋コンクリート構造物は,凍結融解作用によって表層の強度が低下する懸念がある.本研究では,表層が強度低下した構造物の補修・補強に寄与すべく,劣化コンクリートに対する接着系アンカーのせん断抵抗性能の把握を目的とし,コンクリート表層部を凍結融解作用により強度低下させ,せん断載荷実験と有限要素解析を行った.その結果,表層部の強度低下により,アンカー筋の塑性ヒンジ点が深くなり,コンクリートが負担する応力範囲が広がることで,健全時と同程度のせん断抵抗性能を発揮する可能性があることが確認された.journal articl
Key particle properties of shells for cadmium chemisorption
Get PDFapplication/pdfPrevious studies on cadmium adsorption of calcium carbonate have found that polymorph, and, crystallinity are influential factors for adsorbing cadmium ions. The predominant factor for cadmium adsorption has yet to be elucidated because these factors are linked. To overcome this, here each factor is investigated separately. First, atmospheric grinding prepared surf clam (aragonite phase) and scallop (calcite phase) shells with similar crystallite sizes and specific surface areas. Using adsorption isotherm models, kinetics, X-ray diffraction analysis, and TEM observations, both calcite and aragonite react with cadmium to form cadmium carbonate. The chemisorption follows the adsorption mechanism reported in the literature. Based on the Langmuir isotherm model fitting, the maximum adsorbed amount for the ground surf clam shells is 633.3 mg/g, while that for scallop shells is 195.8 mg/g. Then fine surf clam shell particles with a similar specific surface area, and with a relatively wide range of the aragonite ratio, and crystallite size are prepared via a combination of grinding and a subsequent calcination process. Our experiments where one explanatory variable is changed at a time demonstrate that the polymorph ratio and crystallite size of the ground shells play key roles in the chemisorption.journal articl
Practice and problem of remote-learning class under COVID-19 pandemic
Get PDFapplication/pdfIn Hokkaido, infection of a traveler from overseas on January 28 2020 was confirmed. After that, due the number of infected people increase rapidly in in Hokkaido, the "Hokkaido Emergency Declaration" was announced on February 28, 2020 (until March 19, 2020). At the same time, the Crisis Management Countermeasures Office in Muroran Institute of Technology was launched to discuss educational correspondence and contermeasures on COVID-19 infection. As a result, we could start the first semester class on April 22 2019. In this special issue, we review on the attempts (practice and problem) of Remote-learning class on COVID-19 infection in Muroranon Institute of Technology. In particular, (1) preparation of educational environments, (2) construction of remote-learning system and (3) current problems of remote-learing class and improvements in the future are reported.特集departmental bulletin pape
Feedforward control input generation method for a crane system with restrictions on drive system
No full textapplication/pdfThis study proposes a feedforward (FF) control input generation method that can realize automatic anti-sway transport of a suspended load for a crane system with restrictions that the trolley can only accelerate or decelerate at a constant rate; the switching frequency of the acceleration input cannot be too high. First, a time-continuous FF control input is derived by the FF control input generation using the time-polynomial (FFT) method, which is the basis of our method. Next, the FF control input derived by the FFT method is approximated using the pulse width modulation (PWM) control input. In this case, the derived FF control input may be unable to suppress the sway of the suspended load because of the modeling error in deriving the FF control input and the quantization error in approximating the FF control input by the PWM control input. To solve these problems, we propose the update type FF control input generation using the time polynomial (UFFT) method, which evaluates the residual sway at a constant time interval and updates the original FF control input derived by the FFT method. Finally, the effectiveness of the UFFT method is confirmed through simulations and experiments. Our method can achieve anti sway transport that reduces the effects of modeling and quantization errors by setting the update frequency of the FF control input and the PWM frequency appropriately. It can search the FF control input that can suppress residual sway even when the control input switching frequency of the controller is not high.journal articl
Successive weak-ferromagnetic transitions in α-Sm2S3
Get PDFMagnetization and specific heat have been investigated for a single crystal and a sintered sample of α-Sm2S3 having an orthorhombic crystal structure. The weak-ferromagnetic transitions have been found and the Curie temperatures are determined as TC1 = 3.6 K and TC2 = 1.8 K from the magnetic specific heat Cmag(T) of a single crystal under no magnetic field. The weak-ferromagnetic features are extremely anisotropic, and the easy-magnetization axis is c which is perpendicular to the longitudinal direction of the needle-like single crystal. The saturation magnetization at T = 2.0 K and H = 100 Oe along the c-axis after field-cooling (FC) is so small as 1/18 of the full moment of Sm3+. The magnetization M(T) after zero-field cooling (ZFC) shows a curious peak at about 4.5 K just above TC1 regardless of the direction of the applied magnetic field for the single crystal. While both M(T) curves of FC/ZFC for the sintered sample show such peaks at about 4.0 K. The Cmag(T) behaves characteristically depending on the direction of the applied magnetic field. The magnetic entropy Smag(T) is also extremely anisotropic for the magnetic-field direction, and the Smag(T) under H//a is almost invariant to the field within 70 kOe. Therefore, it might be useable for controlling MCE effect by its rotating in magnetic field.journal articl
Efficient and practical synthesis of monoalkyl oxalates under green conditions
Get PDFMonoalkyl oxalates are among the most important building blocks being applied to the synthesis of a variety of significant classes of compounds or applied to various cutting-edge reactions. However, their commercial availability is limited. Their synthetic methods are also limited because of the difficulty to synthesize them, and those hitherto reported are carried out in organic solvents often with the use of toxic reagents with mostly low to modest yields. Here we have developed practical synthesis of monoalkyl oxalates in aqueous media by applying the highly efficient selective monohydrolysis reactions of symmetric diesters which we reported previously. The best conditions apply an aqueous NaOH solution with relatively nontoxic THF or acetonitrile as a co-solvent at around 0–5 ℃. The procedures are simple and environmentally friendly without requiring toxic or expensive reagents, yet yielding the corresponding half-esters in high yields with high purities. All the half-esters prepared here are stable over a long period of time. Therefore, our studies are expected to offer practical green methods for the synthesis of monoalkyl oxalates.journal articl
救急車走行と路面性状の統合調査に基づく舗装修繕シナリオ別の救急搬送時間推計
Get PDF北海道では，救急搬送に60分以上を要する地域が多く，さらに，車両振動に注意が必要となる路面損傷箇所が広く分布する．本研究では，道内の三次救急搬送路線を対象に，救急車プローブ調査と路面性状調査を実施し，路面損傷が救急車の走行速度に与える影響を統計モデルにより分析し，複数の舗装修繕シナリオにおける搬送時間を推計した．まず，速度低下には，信号交差点などの道路構造に加えて，ひび割れ率，IRI，低温ひび割れ本数などの路面性状も影響することを明らかにした．搬送時間の推計では，低温ひび割れが1本以上ある100m区間を簡易補修すると現状から約2分短縮でき，また，高水準な路面管理を行う場合に比べ，損傷度が1.5倍増加する場合には，約4分以上の到着遅れが生じる可能性が示唆された．journal articl