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Application of the generalized body-fixed coordinate system for the wave-body interaction problem of a small-depth elastic structure in head seas

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Journal of Hydrodynamics 2021年第6期33卷 1255-1270页

作者： Kyeonguk Heo masashi kashiwagi School of Naval Architecture and Ocean Engineering University of UlsanUlsanKorea Department of Naval Architecture and Ocean Engineering Osaka UniversitySuitaJapan

The body-fixed coordinate system is applied to the wave-body interaction problem of a small-depth elastic structure which has both rigid and elastic body motions in head *** the weakly non-linear assumption,the perturbation scheme is used and the expansion is conducted up to second-order to consider several non-linear *** solve the boundary value problem,linearization is carried out based not on inertial coordinate but on body-fixed coordinate which could be accelerated by a motion of a *** first,the main feature of the application of body-fixed coordinate system for a seakeeping problem is briefly *** that the transformation of a coordinate system is extended to consider an elastic body motion and several physical variables are re-described in the generalized *** has been found that the deformation gradient could be used for the transformation of a coordinate system if several conditions are *** there are only vertical bending in elastic modes and the structure has relatively small depth,these conditions are generally *** calculate an elastic motion of a body,the generalized mode method is adopted and the mode shape is obtained by solving eigen-value problem of dynamic beam *** the boundary condition of the body-fixed coordinate system,the motion effect reflected to free-surface boundary is considered by extrapolating each mode shape to the horizontal direction from a *** last,simple numerical tests are implemented as a validation *** second-order hydrodynamic force of a freely floating hemisphere is first calculated in zero forward speed ***,motion and added resistance of a ship with forward speed are considered at different flexibility to confirm the effect of an elastic body motion in body-fixed coordinate system.

关键词： Hydroelasticity Higher-order boundary element method(HOBEM) generalized mode method perturbation scheme body-fixed coordinate system wave-body interaction

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Negative refraction of deep water waves through water channel network

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Journal of Hydrodynamics 2019年第4期31卷 840-847页

作者： Takahito Iida masashi kashiwagi Department of Naval Architecture and Ocean Engineering Osaka University Suita Osaka 5650871 Japan Research Fellow of Japan Society for the Promotion of Science Chiyoda-ku Tokyo 1020083 Japan

A design method of a negative refractive index for free surface water waves in deep water is presented. To obtain a condition of a negative index, an analogy between water waves in a water channel and electric waves in an electric circuit is employed. An analytical solution of waves around a periodic array of rectangular columns is obtained by a circuit analysis. Attention is not focused on columns but a space among columns, and then the space is regarded as the water channel. Therefore, the circuit analysis can be applied to water waves. One channel is treated as a unit structure and a number of channels are periodically cascaded as a network. The negative refraction and backward waves by a network of the water channels are shown. Since the negative refraction might occur even around simple periodic structures, it is meaningful to understand wave phenomenon around offshore structures and develop innovative technology.

关键词： Negative refractive index backward wave water channel network equivalent circuit deep water

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Numerical study on ship-generated unsteady waves based on a Cartesian-grid method

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Journal of Hydrodynamics 2020年第5期32卷 953-968页

作者： Kyung-Kyu Yang masashi kashiwagi Yonghwan Kim Department of Naval Architecture and Ocean Engineering Seoul National UniversitySeoulKorea Department of Naval Architecture and Ocean Engineering Osaka UniversityOsakaJapan

The added resistance of a ship in waves can be related to ship-generated unsteady *** the present study,the unsteady wave-pattern analysis is applied to calculate the added resistance in waves for two modified Wigley models using a Cartesian-grid *** the present numerical method,a first-order fractional-step method is applied to the velocity-pressure coupling in the fluid domain,and one of volume-of-fluid(VOF)methods is adopted to capture the fluid interface.A ship is embedded in a Cartesian grid,and the volume fraction of the ship inside the grid is calculated by identifying whether each grid is occupied by liquid,gas,and solid *** sensitivity to the location of measuring position of unsteady waves as well as the number of solution grids is *** added resistance computed by direct pressure integration and wave pattern analysis is compared with experimental *** addition,nonlinear characteristics of the added resistance in waves are investigated by detailed analyses of unsteady flow field and resulting wave pattern.

关键词： Unsteady wave pattern added resistance in waves Cartesian-grid method grid convergence index

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Water Wave Focusing Using Coordinate Transformation

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Journal of Energy and Power Engineering 2017年第10期11卷 631-636页

作者： Takahito Iida masashi kashiwagi Department of Naval Architecture and Ocean Engineering Osaka University Osaka 5650871 Japan Research Fellow (DC1) of Japan Society for the Promotion of Science Osaka 5650871 Japan

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A new electric field mill array with each of the mill’s rotor controlled precisely by a GPS module:Equipment and initial results

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Earth and Planetary Physics 2024年第2期8卷 423-435页

作者： Kozo Yamashita Hironobu Fujisaka DaoHong Wang Hiroyuki Iwasaki Kazuo Yamamoto Koichiro Michimoto masashi Hayakawa Department of Production Systems Engineering and Sciences Komatsu UniversityNu 1-3 Shicho-machiKomatsuIshikawa 923-8511Japan Fujisaka Technology Office 1058-5 Yoshizawa-choOhta-shiGunma 373-0019Japan Department of Electrical Electronic and Computer EngineeringGifu University1-1 YanagidoGifu CityGifu 501-1193Japan Cooperative Faculty of Education Gunma University4-2-Aramaki-machiMaebashiGunma 371-8510Japan Department of Electrical and Electronic Engineering Chubu University1200 Matsumoto-choKasugaiAichi 487-8501Japan Independent Researcher Kosenba Town 2-44-11-406Kawagoe CitySaitama350-0036Japan Advanced Wireless&Communications Research Center The University of Electro-Communications1-5-1 ChofugaokaChofuTokyo 182-8585Japan

We have newly designed an electrostatic sensor,called an electric field mill(EFM),to simplify the estimation of the charge position and charge amount transferred by lightning *** is necessary for this remote estimation of the transferred charge to measure electric field changes caused by charge loss at the time of a lightning strike at multiple *** multiple-station measurement of electric field changes,not only speed but also phase for exposure and shielding of the sensing plates inside each EFM of the array should be synchronized to maintain the sensitivities of the deployed ***,there is no such EFM with specified speed and phase control performance of the rotary ***,we developed a new EFM in which the rotary mechanism was controlled consistently to within 3%error by a GPS *** EFMs had been distributed in the Hokuriku area of Japan during the winter season of 2022-2023 for a test *** we describe the design and a simple calibration method for our new EFM *** analysis method based on the assumption of a simple monopole charge structure is also *** validation,locations of assumed point charges were compared with three-dimensional lightning mapping data estimated by radio observations in the MF-HF *** results indicated the validity to estimate transferred charge amounts and positions of winter cloud-to-ground lightning discharges with our new EFM array.

关键词： lightning electrostatic field electric field mill electric field change

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Regeneration mechanisms and therapeutic strategies for neuromuscular junctions in aging and diseases

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Neural Regeneration Research 2025年第1期20卷 193-194页

作者： masashi Fujitani Abu Md Mamun Tarif Yoshinori Otani Department of Anatomy and Neuroscience Faculty of MedicineShimane UniversityShimaneJapan

The neuromuscular junction(NMJ)is an essential synaptic structure composed of motor neurons,skeletal muscles,and glial cells that orchestrate the critical process of muscle contraction(Li et al.,2018).The typical NMJ structure is classically described as having a“pretzel-like”shape in mice(Figure 1),whereas human NMJs have a smaller,fragmented structure throughout *** NMJs exhibit smaller or fragmented endplates,partial denervation,reduced numbers of synaptic vesicles,abnormal presynaptic mitochondria,and dysfunctional perisynaptic Schwann cells(Alhindi et al.,2022).

关键词： aging structure Figure

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Variations of Atmospheric ELF/VLF Radio Noise Due to Seismogenic Modifications in Tropospheric Conductivity

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Open Journal of Earthquake Research 2024年第2期13卷 113-132页

作者： masashi Hayakawa Alexander P. Nickolaenko Hayakawa Institute of Seismo Electromagnetics Co. Ltd. (Hi-SEM) UEC Alliance Center #521 Tokyo Japan The University of Electro-Communications (UEC) Advanced Wireless & Communications Research Center (AWCC) Chofu-shi Tokyo O.Ya. Usikov Institute for Radiophysics and Electronics National Academy of Sciences of the Ukraine Kharkov Ukraine

We suggest a possible explanation of the influence of pre-seismic activity on the registration rate of natural ELF(extremely low frequency)/VLF(very low frequency) pulses and the changes of their characteristics. The main idea is as follows. The distribution of the electric field around a thundercloud depends on the conductivity profile of the atmosphere. Quasi-static electric fields of a thundercloud decrease in those tropospheric regions where an increase of air conductivity is generated by pre-seismic activities due to emanation of radioactive gas and water into the lower atmosphere. The electric field becomes reduced in the lower troposphere, and the probability decreases of the cloud-to-ground (CG) strokes in such “contaminated” areas. Simultaneously, the electric field grows inside and above the thunderclouds, and hence, we anticipate a growth in the number of horizontal and tilted inter-cloud (or intra-cloud) (both termed as IC discharges) strokes. Spatial orientation of lightning strokes reduces vertical projection of their individual amplitudes, while the rate (median number strokes per a unit time) of discharges grows. We demonstrate that channel tilt of strokes modifies the spectral content of ELF/VLF radio noise and changes the rate of detected pulses during the earthquake preparation phase.

关键词： ELF/VLF Radio Noise Earthquake Precursor Pre-Seismic Modification Conductivity Anomaly in the Lower Atmosphere Radioactive Radon Gases CG Lightning Discharges IC Discharges Cloud-to-Ionosphere Discharge

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基于高阶边界元法和波浪交互理论的三维相邻多浮体问题研究

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船舶力学 2012年第5期16卷 504-513页

作者：史琪琪柏木正杨建民崔进举上海交通大学船舶海洋与建筑工程学院上海200240 日本大阪大学

在解决三维相邻多浮体的水动力问题时,正确处理各浮体之间的相互作用是分析计算的关键所在。文章分别运用高阶边界元法和波浪交互理论对一个由箱型浮体组成的三维多浮体问题进行求解,通过对比分析浮体所受波浪力和水下表面压力分布结果... 详细信息

在解决三维相邻多浮体的水动力问题时,正确处理各浮体之间的相互作用是分析计算的关键所在。文章分别运用高阶边界元法和波浪交互理论对一个由箱型浮体组成的三维多浮体问题进行求解,通过对比分析浮体所受波浪力和水下表面压力分布结果,验证两种方法计算结果的精确度,研究该模型的水动力特点;并通过改变各浮体之间的距离,寻求波浪交互理论在求解三维多浮体问题中的适用性,对该方法在浮体间距不满足限制条件时的计算结果进行解释。

关键词：多浮体高阶边界元法波浪交互理论波浪力压力分布

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SPERA Hydrogen System^(TM)by LOHC-MCH Method for Massive Hydrogen Storage and Transportation

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Journal of Environmental Science and Engineering(A) 2024年第2期13卷 50-60页

作者： Yoshimi Okada Kaji Naohiro Osamu Ikeda Kenichi Imagawa Hironori Kawai masashi Nagai Yasuhiro Inoue Frontier Business Division Chiyoda Corporation4-6-2 Minatomirai Nishi-kuYokohama 2208765Japan Hydrogen Business Department Chiyoda Corporation4-6-2 Minatomirai Nishi-kuYokohama 2208765Japan R&D Center Chiyoda Corporation3-13 Moriya-cho Kanagawa-kuYokohama 2208765Japan Technology Development Department Chiyoda Corporation4-6-2 Minatomirai Nishi-kuYokohama 2208765Japan

Expanding the hydrogen energy utilization is essential for decarbonization,and the commercialization of hydrogen energy carrier systems that can“store”and“transport”hydrogen in a large scale is *** organic chemical hydride method incorporates hydrogen atoms into the molecular structure of a LOHC(Liquid Organic Hydrogen Carrier)to store and transport hydrogen in a liquid state under normal temperature and pressure,and is a highly safe method with low business *** has been developing the technology since 2002,completed a pilot demonstration in 2014 and named it the SPERA Hydrogen^(TM) System,and successfully completed an international supply chain demonstration that transports hydrogen from Brunei to Japan in a large scale in 2020,moving to the commercialization ***,Chiyoda is conducting feasibility studies with a number of domestic and foreign companies with the aim of commercializing the system as soon as *** this paper,outline,features,development status and our efforts in commercialization of SPERA HydrogenTM System are introduced.

关键词： Hydrogen carrier LOHC Methylcyclohexane MCH toluene

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三维多浮体水动力学问题中波浪交互理论的参数应用特性探究分析

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科技通报 2012年第7期28卷 1-7,13页

作者：史琪琪柏木正杨建民崔进举上海交通大学船舶海洋与建筑工程学院上海200240 日本大阪大学

波浪交互理论是解决三维多浮体水动力问题的一种有效方法,该方法能正确处理相邻浮体造成的波浪干涉效应,尤其适用于浮体数目较多的场合。文中运用波浪交互理论,对不同间距下一个箱型多浮体系统的水动力问题进行求解,研究其中的关键参数-... 详细信息

波浪交互理论是解决三维多浮体水动力问题的一种有效方法,该方法能正确处理相邻浮体造成的波浪干涉效应,尤其适用于浮体数目较多的场合。文中运用波浪交互理论,对不同间距下一个箱型多浮体系统的水动力问题进行求解,研究其中的关键参数--消逝波模数和傅立叶级数展开项数的变化,对浮体表面压力分布和波浪力等水动力结果所产生的影响,为波浪交互理论在三维多浮体水动力问题上的进一步深入应用提供依据。

关键词：波浪交互理论消逝波模数傅立叶级数展开项多浮体水动力

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