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Current Ramp-up by Microwave Power in the LATE Device

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Plasma Science and Technology 2009年第4期11卷 394-396页

作者： Takashi MAEKAWA Hitoshi TANAKA masaki UCHIDA Graduate School of Energy Science Kyoto University

In the low aspect ratio torus experiment （LATE） device, plasma current is initiated and ramped up to 20 kA solely by microwave power at the electron cyclotron （EC） range of frequency with a ramp of the external vertical field By for the radial equilibrium of plasma torus at larger currents. Measurements suggest that an energetic electron tail in the energy range of about 200 keV carries the current. The line averaged electron density is higher than the plasma cutoff density, suggesting that tail electrons might be driven by electron Bernstein waves modeconverted from the launched electromagnetic waves.

关键词： current ramp-up microwave electron cyclotron range of frequency

Grain refining in weld metal using short-pulsed laser ablation during CW laser welding of 2024-T3 aluminum alloy

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International Journal of Extreme Manufacturing 2019年第4期1卷 34-41页

作者： masaki Kasuga Tomokazu Sano Akio Hirose Division of Materials and Manufacturing Science Graduate School of EngineeringOsaka University2-1 Yamada-okaSuitaOsaka 565-0871Japan

The 2024 aluminum alloy is used extensively in the aircraft and aerospace industries because of its excellent mechanical ***,the weldability of 2024 aluminum alloy is generally low because it contains a high number of solutes,such as copper(Cu),magnesium(Mg),and manganese(Mn),causing solidification *** high speed welding of 2024 aluminum alloy without the use of filler is achieved,the applicability of 2024 aluminum alloys will *** refining is one of the methods used to prevent solidification cracking in weld metal,although it has never been achieved for high-speed laser welding of 2024 aluminum alloy without ***,we propose a short-pulsed,laser-induced,grain-refining method during continuous wave laser welding without ***-on-plate welding was performed on a 2024-T3 aluminum alloy at a welding speed of 1 m min−1 with a single mode fiber laser at a wavelength of 1070 nm and power of 1 *** in and around the molten pool were irradiated with nanosecond laser pulses at a wavelength of 1064 nm,pulse width of 10 ns,and pulse energy of 430 *** grain-refinement effect was confirmed when laser pulses were irradiated on the molten *** grain-refinement region was formed in a semicircular shape along the solid–liquid *** of the vertical section indicate that the grain-refinement region reached a depth of 1 mm along the solid–liquid *** Vickers hardness test results demonstrated that the hardness increased as a result of grain refinement and that the progress of solidification cracking was suppressed in the grain refinement region.

关键词： 2024 aluminum alloy hot cracking laser welding grain refinement dendrite fragmentation short pulsed laser laser ablation

Miniaturization of Bubbles by Shock Waves in Gas-Liquid Two-phase Flow in the Venturi Tube

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Journal of Thermal Science 2021年第3期30卷 1068-1076页

作者： JIANG Xin YASUNOBU Tsuyoshi NAKAMURA Arisa SHIMAZU masaki National Institute of Technology Kitakyushu College KitakyushuFukuoka 802-0985Japan

Fine bubbles have been widely applied in many fields such as industry,medical engineering and ***,many attentions have been paid to the study of fine bubble generations in order to increase the yield while decrease the ***,the generation process of fine bubbles is a quite complicated process in which multiple hydrodynamic forces are interacted in the gas-liquid two-phase *** studies focus on the techniques of the converging-diverging nozzle(venturi tube)generator,which is famous for its simple and cheap features,and generates fine bubbles by using the miniaturization phenomenon of bubbles occurring in the venturi ***,the impact conditions on the amount and size of bubbles such as nozzle geometry and bleed air haven’t been investigated *** this work,we implement many experiments on the venturi tube fine bubble generators with different geometries and generating conditions,and evaluate different factors impacting the production components such as the volume and the bubble *** experimental results show that the supersonic flow filed in the venturi tube promotes the miniaturization of the bubbles,and the convergent angle of the nozzle and air bleed have a great impact on the size and volume of bubbles.

关键词： fine bubble shock wave gas-liquid two-phase flow venturi tube

Organic fluorophores that emit ultraviolet light in the aggregated state

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Aggregate

Aggregate 2022年第2期3卷 22-32页

作者： masaki Shimizu Tsuneaki Sakurai Faculty of Molecular Chemistry and Engineering Kyoto Institute of TechnologyKyotoJapan

Ultraviolet(UV)-emissive organic light-emitting diodes(OLEDs)have attracted growing attention as future UV-lighting sources following *** design and development of highly efficient UV-emissive organic solids are essential for the advancement of *** herein are organic small molecules and polymers that exhibit UV emission in the aggregated state such as crystal,powder,and amorphous *** UV-emissive molecules are in principle limited to those whose photoluminescence(PL)maxima are less than 400 nm and whose PL quantum yields in the aggregated state,which are useful for evaluating the potential of solid-state emitters,are *** cases that electroluminescence(EL)studies are demonstrated,the emission maxima and external quantum efficiencies with the device structures are also *** exceptions are also included whose PL quantum yields are not reported,but UV-EL with an emission maximum of less than 400 nm is demonstrated.

关键词： conjugation light-emitting materials molecular design solid-state emission UV OLEDs

Mantle convection modeling of the supercontinent cycle: Introversion,extroversion, or a combination?

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Geoscience Frontiers 2014年第1期5卷 77-81页

作者： masaki Yoshida M.Santosh Institute for Research on Earth Evolution (IFREE) Japan Agency for MarineeEarth Science and Technology (JAMSTEC) 2-15 Natsushima-choYokosukaKanagawa 237-0061 Japan Division of Interdisciplinary Science Faculty of Science Kochi UniversityAkebono-cho 2-5-1Kochi 780-8520 Japan School of Earth Sciences and Resources China University of Geosciences (Beijing)

The periodic assembly and dispersal of continental fragments, referred to as the supercontinent cycle, bear close relation to the evolution of mantle convection and plate tectonics. Supercontinent formation involves complex processes of ＂introversion＂（closure of interior oceans）, ＂extroversion＂（closure of exterior oceans）, or a combination of these processes in uniting dispersed continental fragments, Recent developments in numerical modeling and advancements in computation techniques enable us to simulate Earth＇s mantle convection with drifting continents under realistic convection vigor and rheology in Earth-like geometry （i.e., 3D spherical-shell）. We report a numerical simulation of 3D mantle convection, incorporating drifting deformable continents, to evaluate supercontinent processes in a realistic mantle convection regime. Our results show that supercontinents are assembled by a combi- nation of introversion and extroversion processes. Small-scale thermal heterogeneity dominates deep mantle convection during the supercontinent cycle, although large-scale upwelling plumes intermit- tently originate under the drifting continents and/or the supercontinent.

关键词： Mantle convection Numerical simulation Tectonics Supercontinent cycle Introversion Extroversion

Degenerate slave-makers,but nevertheless slave-makers?Host worker relatedness in the ant Myrmoxenus kraussei

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Integrative Zoology 2015年第2期10卷 182-185页

作者： masaki SUEFUJI Jürgen HEINZE Zoology/Evolutionary Biology University of RegensburgGermany

Socially parasitic ants of the formicoxenine genus Myrmoxenus exhibit considerable diversity in colony structure and life *** some species are active slave-makers with many workers and others are workerless‘murder-parasites,’Myrmoxenus kraussei is considered as a‘degenerate slave-maker’because of its very low worker ***,we document that Temnothorax recedens host workers in single colonies of *** from Lago di Garda,Italy,exhibit significantly more genetic diversity than workers in unparasitized *** raises the possibility that,despite its low worker numbers,*** may actively engage in slave raids in nature.

关键词： dulosis nestmate relatedness Myrmoxenus social parasitism slave-making

Conjecture with water and rheological control for subducting slab in the mantle transition zone

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Geoscience Frontiers 2015年第1期6卷 79-93页

作者： Fumiko Tajima masaki Yoshida Eiji Ohtani University of California at Irvine 4164 Frederick Reines Hall4IrvineCA 92697USA Institute for Research on Earth Evolution(IFREE) Japan Agency for Marine-Earth Science and Technology(JAMSTEC) Department of Earth and Materials Science Graduate School of ScienceTohoku University

Seismic observations have shown structural variation near the base of the mantle transition zone （MTZ） where subducted cold slabs, as visualized with high seismic speed anomalies （HSSAs）, flatten to form stagnant slabs or sink further into the lower mantle. The different slab behaviors were also accompanied by variation of the ＂660 kin＂ discontinuity depths and low viscosity layers （LVLs） beneath the MTZ that are suggested by geoid inversion studies. We address that deep water transport by subducted slabs and dehydration from hydrous slabs could affect the physical properties of mantle minerals and govern slab dynamics. A systematic series of three-dimensional numerical simulation has been conducted to examine the effects of viscosity reduction or contrast between slab materials on slab behaviors near the base of the MTZ. We found that the viscosity reduction of subducted crustal material leads to a sepa- ration of crustal material from the slab main body and its transient stagnation in the MTZ. The once trapped crustal materials in the MTZ eventually sink into the lower mantle within 20 30 My from the start of the plate subduction. The results suggest crustal material recycle in the whole mantle that is consistent with evidence from mantle geochemistry as opposed to a two-layer mantle convection model. Because of the smaller capacity of water content in lower mantle minerals than in MTZ minerals, dehydration should occur at the phase transformation depth, ~660 kin. The variation of the disconti- nuity depths and highly localized low seismic speed anomaly （LSSA） zones observed from seismic P waveforms in a relatively high frequency band （~ 1 Hz） support the hypothesis of dehydration from hydrous slabs at the phase boundary. The LSSAs which correspond to dehydration induced fluids are likely to be very local, given very small hydrogen （H＋） diffusivity associated with subducted slabs. The image of such local LSSA zones embedded in HSSAs may not be necessarily captured

关键词： Stagnant slab Discontinuity depth variation Deep water transport by subduction Crustal separation Crustal recycling

Prediction of Photosynthetic Carbon Assimilation Rate of Individual Rice Leaves under Changes in Light Environment Using BLSTM-Augmented LSTM

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Computer Modeling in Engineering & Sciences 2022年第12期133卷 557-577页

作者： Masayuki Honda Kenichi Tatsumi masaki Nakagawa Graduate School of Bio-Applications and Systems Engineering Tokyo University of Agriculture and TechnologyKoganei City184-8588Japan Institute of Agriculture Tokyo University of Agriculture and TechnologyFuchu City183-0054Japan Institute of Engineering Tokyo University of Agriculture and TechnologyKoganei City184-8588Japan

A model to predict photosynthetic carbon assimilation rate(A)with high accuracy is important for forecasting crop yield and *** short-term memory(LSTM),a neural network suitable for time-series data,enables prediction with high accuracy but requires mesophyll *** addition,for practical use,it is desirable to have a technique that can predict A from easily available *** this study,we propose a BLSTM augmented LSTM(BALSTM)model,which utilizes bi-directional LSTM(BLSTM)to indirectly reproduce the mesophyll variables required for *** most significant feature of the proposed model is that its hybrid architecture uses only three relatively easy-to-collect external environmental variables—photosynthetic photon flux density(Q_(in)),ambient CO_(2) concentration(C_(a)),and temperature(T_(air))—to generate mesophyll CO_(2) concentration(C_(i))and stomatal conductance to water vapor(g_(sw))as intermediate ***,A is predicted by applying the obtained intermediate outputs to the learning ***,in this study,1)BALSTM(Q_(in),C_(a),T_(air))had a significantly higher A prediction accuracy than LSTM(Q_(in),C_(a),T_(air))in case of using only Q_(in),C_(a),and T_(air);2)BALSTMC_(i),g_(sw),which had C_(i) and g_(sw) as intermediate products,had the highest A prediction accuracy compared with other candidates;and 3)for samples where LSTM(Q_(in),C_(a),T_(air))had poor prediction accuracy,BALSTMC_(i),g_(sw)(Q_(in),C_(a),T_(air))clearly improved the ***,it was found that incorrect predictions may be formed when certain factors are not reflected in the data(e.g.,timing,cultivar,and growth stage)or when the training data distribution that accounts for these factors differs from the predicted data ***,a robust model should be constructed in the future to improve the prediction accuracy of A by conducting gasexchange measurements(including a wide range of external environmental values)and by increasing the

关键词： Hybrid prediction model assimilation rate leaf internal variables recurrent neural network fluctuating light environments rice

Model Analysis of Radar Echo Split Observed in an Artificial Cloud Seeding Experiment

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Journal of Meteorological Research 2016年第3期30卷 386-400页

作者： masaki Shimada KIKURO Tomine KOJI Nishiyama Department of Earth and Ocean Sciences National Defense Academy Faculty of Engineering Kyushu University

An artificial cloud seeding experiment was performed over the Japan Sea in winter to show how massive seeding could be effective to mitigate heavy snowfall *** results showed that 20 min after cloud seeding,a portion of the radar echo beneath the seeding track was weakened to divide the radar echo into two *** order to analyze the results,a numerical simulation was conducted by using the Weather Research and Forecasting model verion *** this simulation,the seeding effects were represented as phenomena capable of changing rain particles by accreting cloud ice and snow to form graupel particles and by changing cloud liquid water to snow *** graupel particles fell rapidly,thus temporarily intensifying the rainfall,which subsequently ***,the weakened radar echo in the field experiment is deemed to have been caused by the increase in rapidly falling graupel particles.

关键词： heavy snowfall artificial cloud seeding numerical experiment