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Numerical investigation of velocity distribution of turbulent flow through vertically double-layered vegetation

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Water Science and Engineering 2019年第4期12卷 319-329页

作者： Naveed Anjum Norio tanaka Graduate School of Science and Engineering Saitama UniversitySaitama 338-8570Japan International Institute for Resilient Society Saitama UniversitySaitama 338-8570Japan

The velocity structures of flow through vertically double-layered vegetation(VDLV)as well as single-layered rigid vegetation(SLV)were investigated computationally with a three-dimensional(3D)Reynolds stress turbulence model,using the computational fluid dynamics(CFD)code *** detailed velocity distribution was explored with a varying initial Froude number(Fr),with consideration of the steady subcritical flow conditions of an inland *** VDLV flows,the numerical model successfully captured the inflection point in the profiles of mean streamwise velocities in the mixing-layer region around the top of short submerged *** upward and downward movement of flow occurred at the positions located just behind the tall and short vegetation,***,higher streamwise velocities were observed in the upper vegetation layer due to high porosity,with Pr=98%(sparse vegetation,where Pr is the porosity),as compared to those in the lower vegetation layer,which had comparatively low porosity,with Pr=91%(dense vegetation).A rising trend of velocities was found as the flow passed through the vegetation region,followed by a clear sawtooth distribution,as compared to the regions just upstream and downstream of vegetation where the flow was almost *** VDLV flows,a rising trend in the flow resistance was observed with the increase in the initial Froude number,i.e.,Fr?0.67,0.70,and ***,the flow resistance in the case of SLV was relatively very *** numerical results also show the flow structures within the vicinity of short and tall vegetation,which are difficult to attain through experimental measurements.

关键词： Vertically double-layered vegetation Single-layered rigid vegetation Numerical modeling FLUENT Velocity distribution Turbulent flow

Morrey Spaces for Non-doubling Measures

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Acta Mathematica Sinica,English Series 2005年第6期21卷 1535-1544页

作者： Yoshihiro SAWANO Hitoshi tanaka Graduate. School of Mathematical Sciences The University of Tokyo 3-8-1 KomabaMeguro-ku Tokyo 153-8914 Japan

The authors give a natural definition of Morrey spaces for Radon measures which may be non-doubling but satisfy certain growth condition, and investigate the boundedness in these spaces of some classical operators in ... 详细信息

关键词： Morrey space non-doubling measure vector-valued

Energy,economic and environmental assessment of photocatalytic methane production:a comparative case study between Japan and Malaysia

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Global Energy Interconnection 2022年第2期5卷 192-205页

作者： Yudai tanaka M.Hasanuzzaman Graduate School of Energy Science Kyoto UniversityYoshida HonmachiSakyoKyoto 606-8501Japan Higher Institution Centre of Excellence(HICoE) UM Power Energy Dedicated Advanced Centre(UMPEDAC)Level 4Wisma R&DUniversity of MalayaJalan Pantai Baharu59990 Kuala LumpurMalaysia

Photocatalytic methane(CH_(4))production wherein CO_(2)is reduced to CH_(4) by utilizing solar radiation energy is gaining research and industrial focus because of its environmental-friendly *** offers twofold advantages:reduction in CO_(2)emission and production of artificial natural gas(methane)at the same *** this paper,comparative energy,economic and environmental assessment of such photocatalytic methane production has been carried out between Japan and Malaysian *** on the photocatalytic methane production plant and estimation of energy production,CO_(2)emission reduction,and economic indicators are made based on previous research and existing *** analysis shows that Malaysia has a higher potential for energy production and CO_(2)emission reduction than *** analysis reveals that the feasible reaction efficiencies of the plant in Japan and Malaysia are 8%.The slightly higher conversion efficiency in Malaysia is due to the energy price and CO_(2)*** the implementation of the photocatalytic methane production plant,the high energy price and CO_(2)tax will work as a driving force.

关键词： Photocatalysis CO_(2)reduction Photocatalytic methane production CO_(2)tax

EFFECTS OF UNDERSCOUR DEPTH AND HORIZONTAL SPACING BETWEEN TWO BED PROTECTION BLOCKS ON STABILITY OF FRONTAL BLOCK

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Journal of Hydrodynamics 2012年第4期24卷 579-588页

作者： SHAH Prem tanaka Norio YAGISAWA Junji Graduate School of Science and Engineering Saitama University Sakura-ku Saitama-shi Saitama Japan

The stability of a river-bed protection block in a flood event is affected by underscouring of the block. The effects of block spacing on block stability were investigated in different underscour conditions. Three blocks were placed at the bottom in a flume, and the underscour depth of the frontal block and distance between the first and second blocks were changed. Drag and lift forces were measured directly in each experimental condition. Particle Image Velocimetry （PIV） was used to visualize the flow and eva- luate the streamline pattern. Pressure measurements around the block to understand the pressure distribution show that the pressure distribution on the rear and bottom surfaces of the block is significantly affected by changes in block spacing and underscour depth. The experimental results show that for the same underscour gap, lift, and drag coefficients decreased with increasing space between the two blocks. In addition, if the underscour gap is increased with the same horizontal spacing, the lift coefficient increases and drag coefficient decreases. These results demonstrate that wider spacing enhance stability of the frontal block in the underscour condition. Moreover, analysis of block stability with changing underscouring and horizontal spacing shows that bed protection blocks seem to have more stability when the gap between two bed protection blocks was equal to height of the blocks.

关键词： bed protection block stability underscouring Particle Image Velocimetry (PIV)

DISTRIBUTED WATER BALANCE WITH RIVER DYNAMIC-DIFFUSIVE FLOW ROUTING MODEL

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Journal of Hydrodynamics 2009年第4期21卷 564-572页

作者： HASSAN Ahmed NORIO tanaka NOBUYUKI Tamai Graduate School of Science and Engineering Saitama University Graduate School Kanazawa Gakuin University

This article focuses on the application of coupling both river dynamic and river diffusive modeling techniques that can be used with distributed water balance model. In an upstream watershed, both overland and river diffusive flows are routed by diffusive wave approximation of the free surface flow equations. In river downstream reaches, the river dynamic flow is routed by one-dimensional dynamic wave equations （full dynamic St. Venant equations with lateral flow）. The developed model is applied in a part of Arakawa River basin, Kanto area, Japan. The geographic data of river cross sections could be accurately represented by an 11-point cross-section approximation. The effects of both the grid size and lateral flow on the simulated results of the river dynamic flow model were studied. The grid size should be greater than the average width of the river cross-sections. The lateral flow from small drainage systems has significant effects on the simulated results using the river dynamic flow model. The simulated results show good and acceptable agreements with the observed flow discharges and water depths. Both the river discharge and water depth at any location of river network of compound channels with one/two complex floodplains could be correctly estimated.

关键词： diffusive model dynamic model natural compound channels floodplains

Recommender system for discovery of inorganic compounds

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npj Computational Materials 2022年第1期8卷 2084-2090页

作者： Hiroyuki Hayashi Atsuto Seko Isao tanaka Department of Materials Science and Engineering Kyoto UniversityKyotoJapan Nano Research Laboratory Japan Fine Ceramics Center(JFCC)NagoyaJapan

A recommender system based on experimental databases is useful for the efficient discovery of inorganic ***,we review studies on the discovery of as-yet-unknown compounds using recommender *** first method used compositional descriptors made up of elemental *** compositions registered in the inorganic crystal structure database(ICSD)were supplied to machine learning for binary *** other method did not use any descriptors,but a tensor decomposition technique was *** predictive performance for currently unknown chemically relevant compositions(CRCs)was determined by examining their presence in other *** to the recommendation,synthesis experiments of two pseudo-ternary compounds with currently unknown structures were ***,a synthesis-condition recommender system was constructed by machine learning of a parallel experimental data-set collected in-house using a polymerized complex *** scores for unexperimented conditions were then *** experiments under the targeted conditions found two yet-unknown pseudo-binary oxides.

关键词： method. inorganic system

2-D localization system utilizing M-sequence encoded laser beam scanning

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仪器仪表学报 2007年第3期28卷 408-413页

作者： Shinji Ohyama Kiyoshi tanaka Junya Takayama Graduate School of Science and Engineering Tokyo Institute of Technology 2-12-1 O-okayama Meguro-ku Tokyo 152-8552 Japan

In this paper, as the active position measurement system, a novel method for a two-dimensional localization system using M-sequence signal is proposed. The feature of this system is to realize a position measurement only by scanning the encoded laser beams from fixing points to a measurement field, and by observing it. First, both the system configuration and encoding method were practically considered, and an order and an initial value of M-sequence signal were selected for encoding. This method is based on discrete angle measurement therefore the resolution has its own limitation. To overcome this limitation, analogue phase shift detecting method was introduced. System design was performed and applied to position measurement experiments. The experimental results show that the measurement error of the analogue method is 1/3 of that of the discrete method.

关键词：激光电子束扫描位置测量二维定位系统 M序列离散法

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

The impact of tropical land-use change on downstream riverine and estuarine water properties and biogeochemical cycles: a review

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Ecological Processes 2021年第1期10卷 528-548页

作者： Yasuaki tanaka Elizerberth Minggat Wardina Roseli Environmental and Life Sciences Faculty of ScienceUniversiti Brunei DarussalamJalan Tungku LinkGadong BE1410Brunei Darussalam

Tropical primary forests have been disappearing quickly to make use of the land for commercial ***-use change has an impact on downstream aquatic processes,but those impacts have mainly been studied in temperate climate *** present article reviews the impacts of various tropical land-use changes caused by human activities on downstream riverine and estuarine water properties and biogeochemical cycles,focusing especially on the behaviors of nitrogen(N)and phosphorus(P).Logging of tropical primary forests,subsequent establishment of pasture lands,and occasional wildfire or intentional burning have decreased terrestrial N fixation and increased the discharge of P combined with soils,which has lowered the N:P ratio of dissolved inorganic nutrients in the adjacent stream waters and downstream *** fertilizers and aquacultural practices basically cause nutrient enrichment in downstream riverine and estuarine waters,changing the N:P ratio depending on the ***,urbanization causes eutrophication in many tropical estuaries,where a halocline forms easily because of a warm temperature throughout the year and the water at the bottom of the estuary tends to become hypoxic or ***,the impact of land-use change on aquatic processes may be more serious in tropical regions than in temperate or cold climate regions because of(1)a higher biomass and nutrient stock in original tropical forests;(2)higher precipitation,more frequent episodic flooding,and warmer temperatures in tropical regions;and(3)certain practices that are rapidly expanding in tropical regions such as land-based *** land-use changes are causing downstream nutrient enrichment or disturbance of the nutrient balance at tropical land-sea interfaces,and the overall N:P ratios in the aquatic ecosystem seem to be ***,if proper management is conducted and the discharge of nutrients and soils ceases,tropical aquatic systems may have the pote

关键词： Deforestation Land-use change Eutrophication Water quality Hypoxia Environmental monitoring Aquatic conservation Water resources