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Diffusion and collective motion of rotlets in 2D space

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Chinese Physics B 2020年第6期29卷 37-43页

作者： Daiki Matsunaga Takumi Chodo takuma Kawai Graduate School of Engineering Science Osaka University5608531 OsakaJapan

We investigate the collective motion of rotlets that are placed in a single plane. Due to the hydrodynamic interactions,the particles move through the two-dimensional(2D) plane and we analyze these diffusive motions. By analyzing the scaling of the values, we predict that the diffusion coefficient scales with φ0.5, the average velocity with φ, and relaxation time of the velocity autocorrelation function with φ-1.5, where φ is the area fraction of the particles. In this paper, we find that the predicted scaling could be seen only when the initial particle position is homogeneous. The particle collective motions are different by starting the simulation from random initial positions, and the diffusion coefficient is the largest at a minimum volume fraction of our parameter range, φ = 0.05. The deviations based on two initial positions can be explained by the frequency of the collision events. The particles collide during their movements and the inter-particle distances gradually increase. When the area fraction is large, the particles will result in relatively homogeneous configurations regardless of the initial positions because of many collision events. When the area fraction is small(φ < 0.25), on the other hand, two initial positions would fall into different local solutions because the rare collision events would not modify the inter-particle distances drastically. By starting from the homogeneous initial positions, the particles show the maximum diffusion coefficient at φ≈ 0.20. The diffusion coefficient starts to decrease from this area fraction because the particles start to collide and hinder each other from a critical fraction ~23%. We believe our current work contributes to a basic understanding of the collective motion of rotating units.

关键词： rotlet diffusion Stokes flow

Effect of microstructure on outer surface roughening of magnesium alloy tubes in die-less mandrel drawing

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Journal of Magnesium and Alloys 2022年第10期10卷 2730-2744页

作者： takuma Kishimoto Peihua Du Tsuyoshi Furushima Department of Mechanical and Biofunctional Systems Institute of Industrial ScienceThe University of Tokyo4-6-1 KomabaMeguroTokyo 153-8505Japan

The crystal orientation and outer surface roughening of magnesium alloy tubes were evaluated to clarify the effect of the mandrel on the microstructure and outer surface roughness in die-less mandrel drawing. Locally heated ZM21 tubes with an outer diameter of 6.0 mm and an inner diameter of 3.8 mm were drawn with and without a mandrel. The outer surface roughness and crystal orientation were evaluated in the same measurement area. The results indicated that the outer surface becomes rougher in the die-less mandrel drawing than in die-less drawing for a given outer circumferential strain. The outer surface roughness developed when there was large difference in the pyramidal slip system Schmid factor. Therefore, the slip deformation of the pyramidal slip system seems to be mainly responsible for the outer surface roughening in the die-less mandrel drawing. Furthermore, the crystal grain with the {2110} crystal plane vertical to the normal direction of outer surface had a larger Schmid factor than the other crystal grains. The large number of crystal grains with the {2110} crystal plane in the die-less mandrel drawing is one of the reasons that the outer surface roughness develops more in the die-less mandrel drawing than in die-less drawing for a given outer circumferential strain. These results will contribute significantly to the development of fabrication process of the microtube with high surface quality, which prevents rapid corrosion of biomedical applications.

关键词： Tube forming Die-less drawing Surface roughness Crystal plasticity Magnesium alloy Electron backscatter diffraction

Effects of tropical forest conversion into oil palm plantations on nitrous oxide emissions:A meta-analysis

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Journal of Forestry Research 2023年第3期34卷 865-869页

作者： Taiki mori Kyushu Research Center Forestry and Forest Products Research InstituteFFPRIKurokami 4-11-16Kumamoto 860-0862Japan

Oil palm plantations have dramatically expanded in tropical Asia over the past *** their establishment has been projected to increase nitrous oxide(N_(2)O)emissions,earlier reports have shown inconsistent *** study analyzed these previously published data to compare N_(2)O emissions in oil palm plantations to reference forests.A linear mixed-eff ects model was used to examine the signifi cance of the eff ect of establishing oil palm plantations on N_(2)O emissions,rather than to calculate mean eff ect sizes because of limitations in the data *** results indicated that N_(2)O emissions were signifi cantly greater from oil palm plantations than from reference forests,as *** is the fi rst study to report the eff ect of oil palm plantations on N_(2)O emissions by synthesizing previously published *** quantify the size of this eff ect,additional studies with frequent and long-term monitoring data are needed.

关键词： Meta-analysis Nitrogen fertilization Nitrous oxide Oil palm plantation Tropical forest

Level-of-Detail Rendering of Large-Scale Irregular Volume Datasets Using Particles

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Journal of Computer Science & Technology 2010年第5期25卷 905-915页

作者： takuma Kawamura Naohisa Sakamoto Koji Koyamada Member, IEEE Graduate School of Engineering Kyoto University Kyoto 6068501 Japan Center for the Promotion of Excellence in Higher Education Kyoto University Kyoto 6068501 Japan

This paper describes a level-of-detail rendering technique for large-scale irregular volume *** is well known that the memory bandwidth consumed by visibility sorting becomes the limiting factor when carrying out volume rendering of such *** develop a sorting-free volume rendering technique,we previously proposed a particle-based technique that generates opaque and emissive particles using a density function constant within an irregular volume cell and projects the particles onto an image plane with *** the density function changes significantly in an irregular volume cell,the cell boundary may become prominent,which can cause blocky *** the number of the sub-pixels increases,the required frame buffer tends to be *** solve this problem,this work proposes a new particle-based volume rendering which generates particles using metropolis sampling and renders the particles using the ensemble average. To confirm the effectiveness of this method,we applied our proposed technique to several irregular volume datasets,with the result that the ensemble average outperforms the sub-pixel average in computational complexity and memory usage. In addition,the ensemble average technique allowed us to implement a level of detail in the interactive rendering of a 71-million-cell hexahedral volume dataset and a 26-million-cell quadratic tetrahedral volume dataset.

关键词： large-scale irregular volume level-of-detail volume rendering of unstructured meshes

Advances in titanium alloys and orthopedic implants:new titanium alloys and future research directions

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Bio-Design and Manufacturing 2024年第6期7卷 1053-1054页

作者： Yu mori Naoko mori Department of Orthopaedic Surgery Tohoku University Graduate School of MedicineSendai 980-8574Japan Department of Radiology Akita University Graduate School of MedicineAkita 010-8543Japan

Dear Editor,We read with great interest the article by Tan et ***“Accelerated fracture healing by osteogenic Ti45Nb implants through the PI3K-Akt signaling pathway”[1].This research thoroughly examines the bone-forming capabilities of the Ti45Nb *** in vitro studies revealed that the Ti45Nb alloy enhances the osteogenic differentiation of MC3T3-E1 cells more effectively than Ti6Al4V alloy controls,showing no noticeable cytotoxic effects.

关键词： Ti6Al4V alloy

A new complex plant for carbonization and composting of municipal wastes

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Particuology 2010年第6期8卷 599-601页

作者： Shigekatsu mori Nagoya University 2-17-4 MinamigaokaNishinAichi 470-0114Japan

A new complex plant for carbonization and composting of municipal wastes proposed for Gero City is introduced. The separated combustible waste and non-separated combustible waste are carbonized in two fluidized carbonization furnaces in the plant, and the coke produced is used in steelworks. The separated garbage and forest-wastes are mixed with dried septic-tank sludge to produce high quality compost for farms. This use of waste materials in the complex plant considerably lowers the amount of waste going to land-fills, and in addition, creates lower total emission of dioxins and carbon dioxide into the environment.

关键词： Fluidized carbonization Composting plant Municipal wastes Forest wastes Septic-tank sludge Separated collection of trash

Visualization study on the coarse graining DEM for large-scale N gas-solid flow systems

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Particuology 2021年第6期19卷 24-33页

作者： Yuki mori Mikio Sakai Department of Nuclear Engineering and Management School of EngineeringThe University of Tokyo7-3-1 HongoBunkyo-kuTokyo 113-8656Japan Resilience Engineering Research Center School of EngineeringThe University of Tokyo7-3-1 HongoBunkyo-kuTokyo 113-8656Japan

Gas-solid flows are ubiquitous in industrial *** coupled model of the discrete element method(DEM)and computational fluid dynamics(CFD)is one of the techniques for the simulation of the gas-solid *** enhance the applicability of the DEM-CFD method,the coarse graining DEM has been developed to simulate large-scale powder *** coarse graining DEM is a scaling law model and hence can simulate large-scale systems using a smaller number of particles than the actual *** the coarse graining DEM enables to effectively simulate large-scale powder systems on a single PC,visualized image is lack of reality due to reduced spatial *** a novel visualization method is developed to produce realistic *** the proposed technique,the virtual particles are located by considering the motion and location of the coarse grain *** show the adequacy of the proposed method,two types of visualization based on the computational results are made:a blow-up of powder due to injected gas flow and a spouted *** these systems,the visualized images are shown to be improved by the proposed visualization *** effectiveness of the proposed method is proved by the agreement of the images based on the calculation results between the standard DEM-CFD method and coarse graining DEM.

关键词： DEM-CFD method Coarse graining DEM Computer graphics

Image of Ne Trap by a Microwave Cavity

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Chinese Physics Letters 1997年第2期14卷 93-95页

作者： XU Lei Satoshi Oishi Kazuko Shimizu Hiroshi takuma Fujio Shimizu Department of Physics Fudan UniversityShanghai 200433 Institute for Laser Science The University of Electro-communicationsChofugaokaChofushiTokyo 182Japan Department of Applied Physics University of TokyoBunkyo-kuTokyo 113Japan

The focusing of Ne metastable atoms trapped in magnetic-optical trap by a microwave cavity was *** cavity was operated at TM010 *** a microwave power of 14W,the Ne trap was imaged to a spot of about 0.25mm(full width ... 详细信息

关键词： microwave Microwave cavity

Phenyl-triggered photophysical switching between normal fluorescence and delayed fluorescence in phthalonitrile-based luminophores

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Aggregate

Aggregate 2021年第1期2卷 145-150页

作者： In Seob Park Hyukgi Min takuma Yasuda INAmori Frontier Research Center(IFRC) Kyushu UniversityFukuokaJapan Department of Applied Chemistry Graduate School of EngineeringKyushu UniversityFukuokaJapan

Herein,a facile strategy for switching luminescent properties between normal fluorescence and thermally activated delayed fluorescence(TADF)is *** luminophoric molecules,VPN-Ph and VPN-H,combining phthalonitrile as an electron-accepting core and triphenylamines as electron-donating peripheries with and without two phenyl groups,are newly developed.A comparative study on their structural and photophysical properties is *** non-phenyl VPN-H does not exhibit TADF but normal fluorescence,phenyl-introduced VPNPh exhibits TADF with a high photoluminescence quantum yield as a consequence of the phenyl-triggered steric *** virtue of the TADF feature,an organic light-emitting diode(OLED)incorporating VPN-Ph as an emitter achieves a maximum external electroluminescence(EL)quantum efficiency as high as 28.0%,which is five times higher than that of the VPN-H-based ***,phenyl-triggered geometric modulation has a drastic impact on the resulting photophysical and EL properties,leading to TADF on/off switching.

关键词： intramolecular charge transfer molecular orientation organic light-emitting diodes photophysical switching phthalonitrile thermally activated delayed fluorescence