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Natural Convection Melting in a Rectangular Heat Storage Tank of Carbon Nanotube Dispersed Latent Heat Storage Material

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Journal of Thermal Science 2024年第3期33卷 847-855页

作者： Shin-ichi MORITA Tomoya SAITO Kazunori TAKAI yasutaka HAYAMIZU Naoto HARUKI Division of Mechanical and Electrical Engineering Kitami Institute of Technology165 Koen-choKitami-shiHokkaido090-8507Japan National Institute of Technology Yonago College4448 Hikona-cyoYonago-shiTottori683-8502Japan Okayama Prefectural University 111 KubokiSoja-shiOkayama719-1197Japan

A dispersion system fluid can convect even if the dispersoid is a solid ***,heat exchange performance can be improved while maintaining fluidity using a material with high thermal conductivity as the *** study presents the melting performance evaluation results of a latent heat storage material with a carbon nanotube(CNT)dispersion system with high thermal conductivity,which enhances the thermal conductivity of the latent heat storage material and does not limit free *** the thermal conductivity and enhancing the melting convection of the heat storage material result in increased latent heat storage *** this study,the thermal conductivity of the latent heat storage material was successfully increased by dispersing CNTs in the *** 0.1%(in mass)of multi-wall CNT(MWCNT)was dispersed in a paraffin-based latent heat storage material,the shear stress increased by 1.5 times at a shear rate of 500 s^(-1),while taking into account the potential effects of convective ***,a latent heat storage experiment was conducted in a rectangular heat storage tank using the CNT dispersion composition ratio as a parameter.A rectangular vessel with a heated vertical surface was used for the latent heat storage *** melting speed was determined by comparing the amount of latent heat stored in a CNT-dispersed latent heat storage material and a single-phase latent heat storage material *** experimental results show that the time required for the latent heat storage material to completely melt in the heat storage tank was the shortest for the single-phase latent heat storage material ***,the fastest melting progress was observed for the sample with 0.02%(in mass)MWCNT content in the melting rate range of up to approximately 40%in the *** results indicate that this phenomenon is caused by the difference in the melting rates in the upper part of the *** generated data are useful for det

关键词： latent heat storage phase change carbon nano tube free convection heat transfer

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Poly(ethylenimine)-assisted synthesis of hollow carbon spheres comprising multi-sized Ni species for CO_(2)electroreduction

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Chinese Journal of Catalysis 2024年第9期64卷 66-76页

作者： Kaining Li yasutaka Kuwahara Hiromi Yamashita Division of Materials and Manufacturing Science Graduate School of EngineeringOsaka University2‐1 Yamada‐okaOsaka 565‐0871Japan Innovative Catalysis Science Division Institute for Open and Transdisciplinary Research Initiatives(OTRI)Osaka University2‐1 Yamada‐okaSuitaOsaka 565‐0871Japan

Electrochemical CO_(2)reduction to produce value-added chemicals and fuels is one of the research hotspots in the field of energy *** development of efficient catalysts with high conductivity and readily accessible active sites for CO_(2)electroreduction remains challenging yet *** this work,a reliable poly(ethyleneimine)(PEI)-assisted strategy is developed to prepare a hollow carbon nanocomposite comprising a single-site Ni-modified carbon shell and confined Ni nanoparticles(NPs)(denoted as Ni@NHCS),where PEI not only functions as a mediator to induce the highly dispersed growth of Ni NPs within hollow carbon spheres,but also as a nitrogen precursor to construct highly active atomically-dispersed Ni-Nx *** from the unique structural properties of Ni@NHCS,the aggregation and exposure of Ni NPs can be effectively prevented,while the accessibility of abundant catalytically active Ni-Nx sites can be *** a result,Ni@NHCS exhibits a high CO partial current density of 26.9 mA cm^(-2)and a Faradaic efficiency of 93.0%at-1.0 V ***,outperforming those of its PEI-free *** from the excellent activity and selectivity,the shell confinement effect of the hollow carbon sphere endows this catalyst with long-term *** findings here are anticipated to help understand the structure-activity relationship in Ni-based carbon catalyst systems for electrocatalytic CO_(2)***,the PEI-assisted synthetic concept is potentially applicable to the preparation of high-performance metal-based nanoconfined materials tailored for diverse energy conversion applications and beyond.

关键词： Hollow carbon sphere Ni nanoparticle CO_(2)reduction Electrocatalysis Single-atom catalyst

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High performance micromachining of sapphire by laser induced plasma assisted ablation(LIPAA)using GHz burst mode femtosecond pulses

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Opto-Electronic Science 2024年第6期3卷 20-29页

作者： Kotaro Obata Shota Kawabata yasutaka Hanada Godai Miyaji Koji Sugioka RIKEN Center for Advanced Photonics(RAP) Wako-shiSaitama 351-0198Japan Faculty of Engineering Tokyo University of Agriculture and TechnologyKoganeiTokyo 184-8588Japan Graduate School of Science and Technology Hirosaki UniversityHirosakiAomori 036-8561Japan

GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the conventional irradiation scheme of fs laser(single-pulse mode).In this paper,we take advantage of the moderate pulse interval of 205 ps(4.88 GHz)in the burst pulse for high-quality and high-efficiency micromachining of single crystalline sapphire by laser induced plasma assisted ablation(LIPAA).Specifically,the preceding pulses in the burst generate plasma by ablation of copper placed behind the sapphire substrate,which interacts with the subsequent pulses to induce ablation at the rear surface of sapphire *** a result,not only the ablation quality but also the ablation efficiency and the fabrication resolution are greatly improved compared to the other schemes including single-pulse mode fs laser direct ablation,single-pulse mode fs-LIPAA,and nanosecond-LIPAA.

关键词： femtosecond laser GHz burst mode ablation LIPAA laser induced plasma assisted ablation sapphire

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Experimental Study on Load Characteristics in a Floating Type Pendulum Wave Energy Converter

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Journal of Thermal Science 2014年第5期23卷 465-471页

作者： Tengen Murakami yasutaka Imai Shuichi Nagata Institute of Ocean Energy Saga University

A floating type pendulum wave energy converter(FPWEC) with a rotary vane pump as the power take-off system was proposed by Watabe et *** *** showed that this device had high energy conversion *** the previous research,the authors conducted 2D wave tank tests in regular waves to evaluate the generating efficiency of FPWEC with a power take-off system composed of pulleys,belts and a *** a result,the influence of the electrical load on the generating efficiency was ***,the load characteristics of FPWEC are pursued experimentally by using the servo motors to change the damping coefficient in this *** a later part of this paper,the motions of the model with the servo motors are compared with that of the case with the same power take-off system as the previous *** the above experiment,it may be concluded that the maximum primary conversion efficiency is achieved as high as 98%at the optimal load.

关键词： pendulum wave energy converter floating type load characteristics primary conversion efficiency

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The Study of Latent Heat Transport Characteristics by Solid Particles and Saccharide Solution Mixtures

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Journal of Thermal Science 2011年第2期20卷 155-160页

作者： Shin-ichi MORITA yasutaka HAYAMIZU Hideo INABA Department of Mechanical Engineering Yonago National College of Technology Tsuyama National College of Technology

The purpose of this study is the development of latent heat transport system by using the mixture of the minute latent heat storage materials and the saccharine solution as medium. The experimental studies are carried out by the evaluation of viscosity and pressure loss in a pipe. Polyethylene (P.E.) is selected as the dispersed minute material that has closeness density (920kg/m3) of ice (917kg/m3). D-sorbitol and D-xylose solutions are picked as continuum phase of the test mixture. The concentration of D-sorbitol solution is set 48mass% from measured results of saturation solubility and the melting point. 40mass% solution of D-xylose is selected as the other test continuum phase. The non-ion surfactant, EA157 Dai-ichiseiyaku CO. Ltd, is used in order to prevent of dispersed P.E. powder cohere. The pressure loss of test mixture is measured by the straight circular pipe that has smooth inner surface. The measuring length for pressure loss is 1000 mm, and the inner diameter of pipe is 15mm. The accuracy of experiment apparatus for measuring pressure loss is within ±5%. The pressure loss data is estimated by the relationship between the heat transport ratio and the required pump power. It is clarified that the optimum range of mixing ratio exists over 10mass% of latent heat storage material.

关键词： Latent heat transport Heat storage Multiphase flow

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Heat Transfer Efficiency Evaluation for Outward and Inward Multi-Flame-Hole Gas Burner

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Journal of Thermal Science 2012年第2期21卷 189-195页

作者： Shin-ichi MORITA yasutaka HAYAMIZU Takashi KATAYAMA Hideo INABA Department of Mechanical Engineering Yonago National College of Technology 4448 Hikona-cho Yonago city Tottori 683-8502 Japan Department of System Production Engineering Yonago National College of Technology Advanced Course 4448 Hikona-cho Yonago city Tottori 683-8502 Japan Tsuyama National College of Technology 624-1 Numa Tsuyama city Okayama 708-8509 Japan

The purpose of this study is to understand the factor that influence the heating efficiency of the outward and inward multi-hole gas burner. The flame-hole angle and the distance from flame hole to heating object are chosen as the experimental parameters. The measurement of the flame temperature distribution is carried out on each experimental condition. The observation of combustion flame, by the Schlieren method, is done from the purpose to understand the combustion phenomenon on the heating efficiency. LPG (Liquefied petroleum gas) is used for the test fuel gas. The compositions of LPG are propane 97.5vol%, butane 0.2vol% and methane + ethylene 2.3vol%. The optimum ranges of the flame-hole angle and the distance from flame hole to heating object are clarified. The experimental correlation equations for the outward and inward multi-flame-hole gas burner are proposed.

关键词： Burner Heat Transfer Design Thermal Efficiency Energy Saving

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Ru complex and N,P-containing polymers confined within mesoporous hollow carbon spheres for hydrogenation of CO_(2)to formate

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Nano Research 2023年第4期16卷 4515-4523页

作者： Guoxiang Yang yasutaka Kuwahara Kohsuke Mori Catherine Louis Hiromi Yamashita Division of Materials and Manufacturing Science Graduate School of EngineeringOsaka University2-1 Yamada-okaSuitaOsaka 565-0871Japan Institute for Open and Transdisciplinary Research Initiatives(OTRI) Osaka University2-1 Yamada-okaSuitaOsaka 565-0871Japan Unit of Elements Strategy Initiative for Catalysts&Batteries(ESICB) Kyoto UniversityKatsuraKyoto 615-8520Japan JST PRESTO4-1-8 HonchoKawaguchiSaitama 332-0012Japan Sorbonne Université CNRSLaboratoire de Réactivitéde SurfaceLRSF-75005 ParisFrance

The development of reliable catalysts with both excellent activity and recyclability for carbon dioxide(CO_(2))hydrogenation is ***,a ternary hybrid heterogeneous catalyst,involving mononuclear Ru complex,N,P-containing porous organic polymers(POPs),and mesoporous hollow carbon spheres(Ru^(3+)-POPs@MHCS)is reported for CO_(2)hydrogenation to *** on comprehensive structural analyses,we demonstrated that Ru^(3+)-POPs were successfully immobilized within *** optimized Ru^(3+)-0.5POPs@MHCS catalyst,which was obtained with about 5 wt.%Ru^(3+)and 0.5 mmol POPs polymers confined into 0.3 g MHCS,exhibited high catalytic activity for CO_(2)hydrogenation to formate(turnover number(TON)>1,200 for 24 h under mild reaction conditions(4.0 MPa,120℃))and improved durability,compared to Ru^(3+)catalysts without POPs polymers(Ru^(3+)-MHCS)and unencapsulated MHCS(Ru^(3+)-0.5POPs)*** improved catalytic performance is attributed to the high surface area and large pore volume of MHCS which favors dispersion and stabilization of Ru^(3+)-***,the MHCS and POPs showed high CO_(2)adsorption ***^(3+)-POPs encapsulated into MHCS reduces the activation energy barrier for CO_(2)hydrogenation to formate.

关键词： heterogeneous catalysis porous organic polymers(POPs) mesoporous hollow carbon spheres CO_(2)hydrogenation formate synthesis

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Uniform Strike-Slip Rate along the Xianshuihe-Xiaojiang Fault System and Its Implications for Active Tectonics in Southeastern Tibet

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Acta Geologica Sinica(English Edition) 2006年第3期80卷 376-386页

作者： HE Honglin RAN Hongliu yasutaka IKEDA Institute of Geology China Earthquake Administration Beijing 100029 China Department of Earth and Planetary Science University of Tokyo Tokyo 113-0033 Japan

Recent studies on the Xianshuihe-Xiaojiang fault system suggest that the Late Quaternary strike-slip rate is approximately uniform along the entire length of the fault zone, about 15±2 mm/a. This approximately uniform strike slip rate strongly supports the clockwise rotation model of the southeastern Tibetan crust. By approximating the geometry of the arc-shaped Xianshuihe-Xiaojiang fault system as a portion of a small circle on a spherical Earth, the 15±2 mm/a strike slip rate corresponds to clockwise rotation of the Southeastern Tibetan Block at the （5.2±0.7）×10^-7 deg/a angular velocity around the pole （21°N, 88°E） relative to the Northeast Tibetan Block. The approximately uniform strike slip rate along the Xianshuihe-Xiaojiang fault system also implies that the Longmeushan thrust zone is not active, or at least its activity has been very weak since the Late Quaternary. Moreover, the total offset along the Xiaushuihe-Xiaojiang fault system suggests that the lateral extrusion of the Southeastern Tibetan Block relative to Northeastern Tibetan Block is about 160 km and 200-240 km relative to the Tarim-North China block. This amount of lateral extrusion of the Tibetan crust should have accommodated about 13-24% convergence between India and Eurasia based on mass balance calculations. Assuming that the slip rate of 15±2 mm/a is constant throughout the entire history of the Xianshuihe-Xiaojiang fault system, 11±1.5 Ma is needed for the Xianshuihe-Xiaojiang fault system to attain the 160 km of total offset. This implies that left-slip faulting on the Xianshuihe-Xiaojiang fault system might start at 11±1.5 Ma.

关键词： Xianshuihe-Xiaojiang fault system southeastern Tibet strike-slip rate active tectonics

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Development of a building information model-guided post-earthquake building inspection framework using 3D synthetic environments

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Earthquake Engineering and Engineering Vibration 2023年第2期22卷 279-307页

作者： Nathaniel M.Levine yasutaka Narazaki Billie F.Spencer Department of Civil and Environmental Engineering University of Illinois at Urbana-ChampaignUrbanaIllinois 61801USA Zhejiang University-University of Illinois at Urbana-Champaign Institute Zhejiang UniversityHaining 314400China

Computer vision-based inspection methods show promise for automating post-earthquake building *** methods survey a building with unmanned aerial vehicles and automatically detect damage in the collected ***,assessing the damage′s impact on structural safety requires localizing damage to specific building components with known design and *** paper proposes a BIM-based automated inspection framework to provide context for visual surveys.A deep learning-based semantic segmentation algorithm is trained to automatically identify damage in *** BIM automatically associates any identified damage with specific building ***,components are classified into damage states consistent with component fragility models for integration with a structural *** demonstrate the framework,methods are developed to photorealistically simulate severe structural damage in a synthetic computer graphics environment.A graphics model of a real building in Urbana,Illinois,is generated to test the framework;the model is integrated with a structural analysis to apply earthquake damage in a physically realistic manner.A simulated UAV survey is flown of the graphics model and the framework is *** method achieves high accuracy in assigning damage states to visible structural *** assignment enables integration with a performance-based earthquake assessment to classify building safety.

关键词： computer vision earthquake engineering building information model physics-based graphics model synthetic environment

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Experimental Study of the Flow in Helical Circular Pipes:Torsion Effect on the Flow Velocity and Turbulence

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Journal of Thermal Science 2008年第3期17卷 193-198页

作者： yasutaka HAYAMIZU Kyoji YAMAMOTO ShinichiroYANASE Toru HYAKUTAKE Toru SHINohARA Shinichi MORITA Department of Mechanical Engineering Yonago National College of Technology Graduate School of Natural Science and Technology Okayama University

An objective of the present paper is to experimentally clarify the torsion effect on the flow in helical circular pipes. We have made six helical circular pipes having different pitches and common non-dimensional curvature δ of about 0.1. The torsion parameter β0, which is defined by β0 = τ/（2δ）1/2 with non-dimensional torsion r, are taken to be 0.02, 0.45, 0.69, 1.01, 1.38 and 1.89 covering from small to very large pitch. The velocity distributions and the turbulence of the flow are measured using an X-type hot-wire anemometer in the range of the Reynolds number from 200 to 20000. The results obtained are summarized as follows： The mean secondary flow pattern in a cross section of the pipe changes from an ordinary twin-vortex type as is seen in a curved pipe without torsion （toroidal pipe） to a single vortex type after one of the twin-vortex gradually disappears as β0 increases. The circulation direction of the single vortex is the same as the direction of torsion of the pipe. The mean velocity distribution of the axial flow is similar to that of the toroidal pipe at small β0, but changes its shape as β0 increases, and attains the shape similar to that in a straight circular pipe when ,β0 = 1.89. It is also found that the critical Reynolds number, at which the flow shows a marginal behavior to turbulence, decreases as ,β0 increases for small ,β0, and then increases after taking a minimum at ,β0 ≈ 1.4 as ,β0 increases. The minimum of the critical Reynolds number experimentally obtained is about 400 at ,β0 ≈ 1.4.

关键词： Helical Circular Pipe Torsion Effect Critical Reynolds Number Turbulence

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