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Influence of Diffuser on Aerodynamic Noise of a Forward Curved Fan

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Journal of Thermal Science 2013年第5期22卷 433-438页

作者： Soichi sasaki Kota SUZUKI Yuta Onomichi Hidechito Hayashi Division of System Science Graduate School of Engineering Nagasaki University1-14 Bunkyo-machi Nagasaki 852-8521 Japan Department of Advanced Engineering Graduate School of Engineering Nagasaki University1-14 Bunkyo-machi Nagasaki 852-8521 Japan

In order to clarify the influence of a diffuser on the charactersfics of a forward curved fan, the influence of the bare ratio and the outlet angle on the characteristics of the fan were measured through an experiment performed with an actual fan as well as through a numerical simulation, respectively. The mechanism of the discrete fre- quency noise generated by the separated flow of the diffuser was analyzed. The optimized bare ratio was ap- proximately 17%. The flow separated inside of the diffuser generated discrete frequency noise owing to the inter- action between the reversed flow from the diffuser and the impeller rotating at the blade passing frequency. The diffuser outlet angle influenced the pressure ratio more than that by the bare ratio. Furthermore, it was confirmed that restraining the separation in the diffuser effectively decreases the fan noise.

关键词： Pressure Drop Fan Aerodynamic Noise Internal Flow Separation

Nonequilibrium molecular dynamics for accelerated computation of ion–ion correlated conductivity beyond Nernst–Einstein limitation

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npj Computational Materials 2023年第1期9卷 1796-1803页

作者： Ryoma sasaki Bo Gao Taro Hitosugi Yoshitaka Tateyama School of Materials and Chemical Technology Tokyo Institute of Technology2-12-1 OokayamaMeguroTokyo 152-8552Japan Center for Green Research on Energy and Environmental Materials National Institute for Material Science1-1 NamikiTsukubaIbaraki 305-0044Japan Department of Chemistry The University of Tokyo7-3-1 HongoBunkyoTokyo 113-0033Japan

Condensed matters with high ionic conductivities are crucial in various solid devices such as solid-state batteries. The conduction ischaracterized by the cooperative ionic motion associated with the high carrier density. However, the high cost of computingcorrelated ionic conductivities has forced almost all ab initio molecular dynamics (MD) to rely on the Nernst–Einstein dilute-solutionapproximation, which ignores the cross-correlation effect. Here we develop a chemical color-diffusion nonequilibrium MD (CCD-NEMD) method, which enables to calculate the correlated conductivities with fewer sampling steps than the conventional MD. ThisCCD-NEMD is demonstrated to well evaluate the conductivities in the representative solid electrolyte bulk Li10GeP2S12 andLi_(7)La_(3)Zr_(2)O_(12). We also applied CCD-NEMD to the grain boundary of Li_(7)La_(3)Zr_(2)O_(12) and demonstrated its applicability for calculatinginterfacial local conductivities, which is essential for investigating grain boundaries and composite electrolytes. CCD-NEMD canprovide further accurate understanding of ionics with ionic correlations and promote developing solid devices.

关键词： dynamics Nernst steps

Coulometric determination of dissolved hydrogen with a multielectrolytic modified carbon felt electrode-based sensor

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Journal of Environmental Sciences 2013年第6期25卷 1077-1082页

作者： Hiroaki Matsuura Yosuke Yamawaki Kosuke sasaki Shunichi Uchiyama Department of Life Science & Green Chemistry Faculty of EngineeringSaitama Institute of Technology Department of Applied Chemistry Graduate School of EngineeringSaitama Institute of Technology

A multielectrolytic modified carbon electrode （MEMCE） was fabricated by the electrolytic-oxidation/reduction processes. First, the functional groups containing nitrogen atoms such as amino group were introduced by the electrode oxidation of carbon felt electrode in an ammonium carbamate aqueous solution, and next, this electrode was electroreduced in sulfuric acid. The redox waves between hydrogen ion and hydrogen molecule at highly positive potential range appeared in the cyclic voltammogram obtained by MEMCE. A coulometric cell using MEMCE with a catalytic activity of electrooxidation of hydrogen molecule was constructed and was used for the measurement of dissolved hydrogen. The typical current vs. time curve was obtained by the repetitive measurement of the dissolved hydrogen. These curves indicated that the measurement of dissolved hydrogen was finished completely in a very short time （ca. 10 sec）. A linear relationship was obtained between the electrical charge needed for the electrooxidation process of hydrogen molecule and dissolved hydrogen concentration. This indicates that the developed coulometric method can be used for the determination of the dissolved hydrogen concentration.

关键词： multielectrolytic modified carbon electrode (MEMCE) coulometric determination dissolved hydrogen

Prediction of Aerodynamic Noise in a Ring Fan Based on Wake Characteristics

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Journal of Thermal Science 2011年第2期20卷 144-149页

作者： Soichi sasaki Masaharu Fukuda Masao Tsujino Haruhiro Tsubota Faculty of Engineering Nagasaki University 1-14 Bunkyo-machi Nagasaki 852-8521 Japan Graduate School of Science and Technology Nagasaki University 1-14 Bunkyo-machi Nagasaki 852-8521 Japan Research Division Komatsu Ltd.1200 Manda Hiratsuka-shi Kanagawa 254-8567 Japan

A ring fan is a propeller fan that applies an axial-flow impeller with a ring-shaped shroud on the blade tip side. In this study, the entire flow field of the ring fan is simulated using computational fluid dynamics (CFD); the accuracy of the CFD is verified through a comparison with the aerodynamic characteristics of a propeller fan of current model. Moreover, the aerodynamic noise generated by the fan is predicted on the basis of the wake characteristics. The aerodynamic characteristic of the ring fan based on CFD can represent qualitatively the variation in the measured value. The main flow domain of the ring fan is formed at the tip side of the blade because blade tip vortex is not formed at that location. Therefore, the relative velocity of the ring fan is increased by the circumferential velocity. The sound pressure levels of the ring fan within the frequency band of less than 200 Hz are larger than that of the propeller fan. In the analysis of the wake characteristics, it revealed that Karman vortex shedding occurred in the main flow domain in the frequency domain lower than 200 Hz ; the aerodynamic noise of the ring fan in the vortex shedding frequency enlarges due to increase in the relative velocity and the velocity fluctuation.

关键词： Fan Vortex Aerodynamic Noise Wake Internal Flow

Effect of dissolved oxygen on methane production from bottom sediment in a eutrophic stratified lake

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Journal of Environmental Sciences 2023年第3期125卷 61-72页

作者： Yasuyuki Maruya Keisuke Nakayama Masafumi sasaki Katsuaki Komai Graduate School of Engineering Kyushu University744 MotookaNishi-KuFukuoka 819-0395Japan Graduate School of Engineering Kobe UniversityRokkodai-Cho 1-1Nada-KuKobe 657-8501Japan Department of Engineering Kitami Institute of TechnologyKohen-Cho 165Kitami 090-8507Japan

Clarifying the role of sulfate and dissolved oxygen (DO) in methane production may allow for precise and accurate modeling of methane emissions in eutrophic *** conducted field observations of sulfate,methane,and DO concentrations in Lake Abashiri,a typical brackish and eutrophic lake in a cold region,to develop a DO-based method for quantitively estimating methane production in a eutrophic lake and analyzed the *** found that sulfate concentrations decreased rapidly from 900.0 mg/L in water overlying the sediments to nearly 0.0 mg/L in the bottom *** production was almost uniform across sediment depths of 0.05 to 0.25 m,ranging from 1400 to 1800μmol/m^(2)/***,methane production was found to be a function of DO concentrations in water overlying the bottom and could be modeled by a logistic function:constant production at 1,400μmol/m^(2)/day for DO concentrations of 0.0 to 3.0 mg/L,rapidly decreasing to 0μmol/m^(2)/day for DO concentrations of 3.0 to 6.0 mg/*** methane model was verified using a simple one-dimensional numerical model that showed good agreement with field *** results thus suggest that the proposed methane model reduces uncertainty in estimating methane production in a eutrophic lake.

关键词： Dissolved oxygen(DO) Stratification Methane Anoxia Numerical simulation

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采空区地下遗煤燃烧-地表碳通量相关性分析

中国安全科学学报 2024年第2期34卷 161-167页

作者：王永军郑倩张河猛董伟张晓明佐佐木久郞辽宁工程技术大学安全科学与工程学院辽宁葫芦岛125105 辽宁工程技术大学矿山热动力灾害与防治教育部重点实验室辽宁葫芦岛125105 九州大学工学府日本福冈819-0385 辽宁工程技术大学工程与环境研究所辽宁葫芦岛125105

为探究复杂条件下地表碳通量对地下遗煤自燃的响应机制,通过长期监测阜新海州露天矿采空区上覆地表碳通量、土壤温度、地表裂缝、环境风速、土壤湿度等数据,并结合现场试验,研究遗煤燃烧与地表碳通量的相关性,分析地表裂缝、环境风速、... 详细信息

为探究复杂条件下地表碳通量对地下遗煤自燃的响应机制,通过长期监测阜新海州露天矿采空区上覆地表碳通量、土壤温度、地表裂缝、环境风速、土壤湿度等数据,并结合现场试验,研究遗煤燃烧与地表碳通量的相关性,分析地表裂缝、环境风速、土壤湿度等因素对地下煤自燃-地表碳通量的影响特征。结果表明:地下遗煤燃烧是触发地表碳通量异常响应的根本因素,碳通量与土壤温度分布呈正相关;裂缝是影响地表碳通量分布的主要因素,环境风速与地表碳通量基本呈正相关,地表碳通量一般不受土壤湿度影响,但受降雨影响较大。

关键词：采空区遗煤燃烧地表碳通量相关性分析地表裂缝环境风速土壤湿度

Selective extraction of In(Ⅲ),Ga(Ⅲ) and Zn(Ⅱ) using a novel extractant with phenylphosphinic acid

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Chinese Journal of Chemical Engineering 2016年第2期24卷 232-236页

作者： Yuji sasaki Naoki Matsuo Tatsuya Oshima Yoshinari Baba Department of Applied Chemistry Faculty of EngineeringUniversity of Miyazaki

A new extractant, [N,N-di（2-ethylhexyl）aminolmethylphenylphosphinic acid （DEAPP）, was synthesized to de- velop the mutual separation techniques of In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ）. The extraction selectivity for In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ） with DEAPP was higher than that of the commercial phosphorus acid extractants such as D2EHPA and PC-88A. The extraction selectivity for metal ions in 1 mob L 1 aqueous ammonium nitrate solution with DEAPP was in the following order： In（Ⅲ）〉 Ga（Ⅲ）〉 Zn（Ⅱ）. These selective extraction behaviors indicate that the amino moiety of DEAPP plays an important role in the mutual separation of ln（Ⅲ）, Ga（Ⅲ） and Zn（ll）. The extraction equilibria of In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ） with DEAPP （ = HR） were expressed by the following reactions： In3＋＋ 2（HR）2 InR3（HR）＋ 3H＋, Ga3＋＋ 1.5（HR）2 ＋ N- = GaR2（HR）（NO3）＋ 2H＋, and Zn2＋ 4- 2（HR）2 ZnR2 （HR） 2 determined 4- 2H＋. The extraction equilibrium constants of In（Ⅲ）, Ga（Ⅲ） and Zn（Ⅱ） with DEAPP were to be Kex, M = 1.7 × 104 [*** 1], 4.17 [（***-1）s], and 1.55 × 10 2 [-], respectively.

关键词： Liquid-liquid extraction Phosphinic acid Indium(Ⅲ) Gallium(Ⅲ) Zinc(Ⅱ) Mutual separation Extraction equilibrium

轻度认知功能障碍病人MRI显示脉络丛增大的大型队列研究

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国际医学放射学杂志 2024年第5期 625-626页

作者： Y.Umemura K.Watanabe S.Kasai S.Ide Y.Ishimoto M.sasaki 陈瑾

目的以往研究表明阿尔茨海默病（AD）可能存在脉络丛（CP）功能障碍，并特别提出MRI所见的CP增大可作为AD预测指标。但探讨CP体积（CPV）与轻度认知障碍

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Event detection and visualization of ocean eddies simulated by ocean general circulation model

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International Journal of Modeling, Simulation, and Scientific Computing 2019年第3期10卷 164-182页

作者： Daisuke Matsuoka Fumiaki Araki Hideharu sasaki Information Engineering Program Research Institute for Value-Added-Information Generation Japan Agency for Marine-Earth Science and Technology(JAMSTEC)3173-25 Showa-machi Kanazawa-kuYokohama 236-0001Japan Application Laboratory(APL)Research Institute for Value-Added-Information Generation Japan Agency for Marine-Earth Science and Technology(JAMSTEC)3173-25 Showa-machi Kanazawa-kuYokohama 236-0001Japan

Numerical study of ocean eddies has been carried out by using high-resolution ocean general circulation *** order to understand ocean eddies from the large volume data produced by simulations,visualizing only eddy distribution at each time step is insufficient;time-variations in eddy events and phenomena must also be ***,existing methods cannot precisely find and track eddy events such as amalgamation and *** this study,we propose an original approach for eddy detection,tracking,and event visualization based on an eddy classification *** proposed method detects streams and currents as well as eddies,and it classifies discovered eddies into several categories using the additional stream and current *** tracking how the classified eddies vary over time,detecting events such as eddy amalgamation and bifurcation as well as the interaction between eddies and ocean currents becomes *** adopt the proposed method for two ocean areas in which strong ocean currents exist as case *** visualize the detected eddies and events in a time series of images,allowing us to acquire an intuitive understanding of a region of interest concealed in a high-resolution data ***,our proposed method succeeded in clarifying the occurrence place and seasonality of each type of eddy event.

关键词： Ocean simulation ocean eddy ocean current visualization