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A New Approach for Refining Carbide Dimensions in M42 Super Hard High-speed Steel

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Journal of Iron and Steel Research International 2016年第8期23卷 800-807页

作者： Xue-feng ZHOU Wang-long ZHU Hong-bing JIANG Feng FANG yi-you tu Jian-qing JIANG Jiangsu Key Laboratory of Advanced Metallic Materials School of Materials Science and EngineeringSoutheast University Nanjing 211189 Jiangsu China Jiangsu Engineering Research Center of Tool and Die Steel Danyang 212312 Jiangsu China Nanjing University of Information Science and Technology Nanjing 210044 Jiangsu China

Obtaining small carbides is crucial but difficult for high-speed steels.A new approach for refining carbide dimensions in M42 super hard high-speed steel by increasing cooling rate and spheroidizing treatment was *** morphologies and properties of eutectic carbides formed at different cooling rates were investigated by means of scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,electron back-scattered diffraction（EBSD）and differential scanning calorimeter（DSC）.The results show that eutectic carbides change from a lamellar shape into a curved-rod shape as cooling rate *** different morphologies,the two carbides are both of M2C type with a hexagonal close-packed structure and display a single crystal orientation in one eutectic *** morphology of M2C mainly depends on the growing process of eutectic carbides,which is strongly influenced by cooling *** with lamellar carbides,M2C carbides with curved-rod shapes are less stable,and decompose into M6 C and MC at lower *** are more inclined to spheroidize during heating,which ultimately and distinguishably refines the carbide *** small carbides are much easier to dissolve into matrices during austenization,the process described herein improves the supersaturation of alloying elements in martensite,which leads to an increment of hardness in M42 steel.

关键词： eutectic lamellar hexagonal carbide heating calorimeter curved dispersive dimensions decompose

Evaluation of the antioxidant effects of four main theaflavin derivatives through chemiluminescence and DNA damage analyses

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2011年第9期12卷 744-751页

作者： Yuan-yuan WU Wei LI yi XU En-hui JIN you-ying tu Department of Tea Science Zhejiang UniversityHangzhou 310058China Key Laboratory of Horticultural Plants Growth Development and Quality ImprovementMinistry of AgricultureZhejiang UniversityHangzhou 310058China Department of Tea Culture Zhejiang Shuren UniversityHangzhou 310015China

Theaflavins(TFs) are the dimers of a couple of epimerized catechins,which are specially formed during black tea *** explore the differences among four main TF derivatives(theaflavin(TF 1),theaflavin3-gallate(TF 2 A),theaflavin-3'-gallate(TF 2 B),and theaflavin-3,3'-digallate(TF 3)) in scavenging reactive oxygen species(ROS) in vitro,their properties of inhibiting superoxide,singlet oxygen,hydrogen peroxide,and the hydroxyl radical,and their effects on hydroxyl radical-induced DNA oxidative damage were systematically analyzed in the present *** results show that,compared with()-epigallocatechin gallate(EGCG),TF derivatives were good antioxidants for scavenging ROS and preventing the hydroxyl radical-induced DNA damage in *** 3 was the most positive in scavenging hydrogen peroxide and hydroxyl radical,and TF 1 suppressed *** antioxidant capacities of TF 2 B on singlet oxygen,hydrogen peroxide,hydroxyl radical,and the hydroxyl radical-induced DNA damage in vitro were *** differences between the antioxidant capacities of four main TF derivatives in relation to their chemical structures were also *** suggest that these activity differences among TF derivatives would be beneficial to scavenge different ROS with therapeutic potential.

关键词： Theaflavin derivatives Black tea Antioxidant capacity DNA oxidative damage

Phase Residual Estimations for PCVs of Spaceborne GPS Receiver Antenna and Their Impacts on Precise Orbit Determination of GRACE Satellites

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Chinese Journal of Aeronautics 2012年第4期25卷 631-639页

作者： tu Jia GU Defeng WU yi yi Dongyun College of Science National University of Defense TechnologyChangsha 410073China

In-flight phase center systematic errors of global positioning system（GPS） receiver antenna are the main restriction for improving the precision of precise orbit determination using dual-frequency *** approach is one of the valid methods for in-flight calibration of GPS receiver antenna phase center variations（PCVs） from ground *** this paper,followed by the correction model of spaceborne GPS receiver antenna phase center,ionosphere-free PCVs can be directly estimated by ionosphere-free carrier phase post-fit residuals of reduced dynamic orbit *** the data processing of gravity recovery and climate experiment（GRACE） satellites,the following conclusions are ***,the distributions of ionosphere-free carrier phase post-fit residuals from different periods have the similar systematic ***,simulations show that the influence of phase residual estimations for ionosphere-free PCVs on orbit determination can reach the centimeter ***,it is shown by in-flight data processing that phase residual estimations of current period could not only be used for the calibration for GPS receiver antenna phase center of foretime and current period,but also be used for the forecast of ionosphere-free PCVs in future period,and the accuracy of orbit determination can be well improved.

关键词： global positioning system precise orbit determination phase center variations phase residual estimation GRACE

tuning the interfacial reaction environment via pH-dependent and induced ions to understand C–N bonds coupling performance in NO3- integrated CO2 reduction to carbon and nitrogen compounds over dual Cu-based N-doped carbon catalyst

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Journal of Energy Chemistry 2025年第1期100卷 273-285页

作者： Tianhang Zhou Chen Shen Zhenghao Wu Xingying Lan yi Xiao College of Carbon Neutrality Future Technology State Key Laboratory of Heavy Oil Processing China University of Petroleum (Beijing) Institute of Materials Science TU Darmstadt Department of Chemistry Xi'an Jiaotong-Liverpool University Department of Mechanical and Mechatronics Engineering and Waterloo Institute of Nanotechnology University of Waterloo Waterloo

Dual atomic catalysts （DAC）,particularly copper （Cu2）-based nitrogen （N） doped graphene,show great potential to effectively convert CO2and nitrate （NO3-） into important industrial chemicals such as ethylene,glycol,acetamide,and urea through an efficient catalytical process that involves C–C and C–N ***,the origin of the coupling activity remained unclear,which substantially hinders the rational design of Cu-based catalysts for the N-integrated CO2reduction reaction （CO2RR）.To address this challenge,this work performed advanced density functional theory calculations incorporating explicit solvation based on a Cu2-based N-doped carbon (Cu2N6C10) catalyst for *** calculations are aimed to gain insight into the reaction mechanisms for the synthesis of ethylene,acetamide,and urea via coupling in the interfacial reaction *** to the sluggishness of CO2,the formation of a solvation electric layer by anions （F-,Cl-,Br-,and I-） and cations (Na+,Mg2+,K+,and Ca2+) leads to electron transfer towards the Cu *** process significantly accelerates the reduction of *** results reveal that*CO intermediates play a pivotal role in N-integrated ***,the Cu2-based N-doped carbon catalyst examined in this study has demonstrated the most potential for C–N coupling to *** findings reveal that through the process of a condensation reaction between*CO and NH2OH for urea synthesis,*NO3-is reduced to*NH3,and*CO2to*CCO at dual Cu atom *** dual-site reduction facilitates the synthesis of acetamide through a nucleophilic reaction between NH3and the ketene ***,we found that the I-and Mg2+ions,influenced by pH,were highly effective for acetamide and ammonia synthesis,except when F-and Ca2+were ***,the mechanisms of C–N bond formation were investigated via ab-initio molecular dynamics simulations,and we found that adjusting the micro-environment can change the dominant side reaction,shift

关键词： pH-dependent micro-environments C–N coupling Dual Cu-based nitrogen carbon catalysts Explicit solvation model Ion stabilizer AIMD

Influencing factor analysis of interception probability and classification-regression neural network based estimation

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Journal of Systems Engineering and Electronics 2023年第4期34卷 992-1006页

作者： NAN yi yi Guoxing HU Lei WANG Changhong tu Zhenbiao Department of Control Science and Engineering Harbin Institute of TechnologyHarbin 150001China Beijing Electro-mechanical Engineering Institute Beijing 100074China

The interception probability of a single missile is the basis for combat plan design and weapon performance evaluation,while its influencing factors are complex and mutually *** calculation methods have very limited analysis of the influence mechanism of influencing factors,and none of them has analyzed the influence of the guidance *** paper considers the influencing factors of both the interceptor and the target more *** parameters include speed,guidance law,guidance error,fuze error,and fragment killing ability,while target performance includes speed,maneuverability,and *** this paper,an interception model is established,Monte Carlo simulation is carried out,and the influence mechanism of each factor is analyzed based on the model and simulation ***,this paper proposes a classification-regression neural network to quickly estimate the interception probability based on the value of influencing *** proposed method reduces the interference of invalid interception data to valid data,so its prediction accuracy is significantly better than that of pure regression neural networks.

关键词： interception probability simulation modeling analysis of influencing factors probability estimation neural networks

Experimental Study on the Performance of an Onboard Hollow-Fiber-Membrane Air Separation Module

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Fluid Dynamics & Materials Processing 2022年第2期18卷 355-370页

作者： yi tu Yu Zeng School of Mechanical Engineering Hunan University of Arts and ScienceChangde415000China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

Onboard air separation devices,based on hollow fiber membranes,are traditionally used for the optimization of aircraft fuel tank inerting *** the present study,a set of tests have been designed and executed to assess the air separation performances of these systems for different air inlet temperatures(70°C∼110°C),inlet pressures(0.1∼0.4 MPa),volume flow rates of nitrogen-enriched air(NEA)(30∼120 L/min)and flight altitudes(1.5∼18 km).In particular,the temperature,pressure,volume flow rate,and oxygen concentration of air,NEA and oxygen-enriched air(OEA)have been *** experimental results show that the oxygen concentration of NEA,air separation coefficient,and nitrogen utilization coefficient decrease with the rising of air inlet temperature,air inlet pressure,and flight *** effect of air inlet pressure on the above three parameters is significant,while the influence of air inlet temperature and flight altitude is relatively small.

关键词： Aircraft fuel tank inerting hollow-fiber-membrane air separation experimental study onboard air separation device

Human’s digital footprints on the Qinghai-Tibet Plateau:Variations during festivals and impacts on nature reserves

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Journal of Geographical Sciences 2021年第2期31卷 179-194页

作者： DU Yunyan tu Wenna LIANG Fuyuan yi Jiawei State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Department of Earth Atmosphericand Geographic Information SciencesWestern Illinois UniversityMacombIL61455USA

Mobile internet and wireless communication technologies have produced unprecedented location-aware *** big geospatial data can be used as a proxy measure of the‘digital footprints’left by us on the planet and provide a valuable opportunity to understand the dynamic and short-term human disturbance on the nature at fine *** study investigated the spatiotemporal variations of human’s digital footprints on the Qinghai-Tibet Plateau using smartphone-users-generated Tencent’s location request *** results showed that human’s digital footprints cover less than 5%of Qinghai and Tibet,exhibiting either a U-shaped or an N-shaped temporal change pattern during the major *** changes of the digital footprints manifested a transition process from dispersion to concentration in Xining and *** disturbance assessment of seven large nature reserves on the plateau showed that the Qinghai Lake is the most disturbed one as shown by 14.6%of its area is stained with human digital footprints and the areal average of footprint intensity is 1.59,and the disturbance was significantly escalated during the National Day *** contrast,the Qangtang and Hoh Xil are the least affected nature reserves with the two indices less than 1%and 0.1,respectively.

关键词： digital footprint space-time variations human impact nature reserve location request

Study of Flow and Heat Transfer in an Ejector-Driven Swirl Anti-Icing Chamber

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Fluid Dynamics & Materials Processing 2024年第5期20卷 989-1014页

作者： yi tu Yuan Wu Yu Zeng Hunan University of Arts and Sciences Hunan Key Laboratory of Distributed Electric Propulsion Vehicle Control TechnologyChangde415000China Liaoning Provincial Key Laboratory of Aircraft Ice Protection AVIC Aerodynamics Research InstituteShenyang110034China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

The formation of ice on the leading edge of aircraft engines is a serious issue,as it can have catastrophic *** Swirl Anti-Icing(SAI)system,driven by ejection,circulates hot fluid within a 360°annular chamber to heat the engine inlet lip surface and prevent *** study employs a validated Computational Fluid Dynamics(CFD)approach to study the impact of key geometric parameters of this system on flow and heat transfer characteristics within the anti-icing ***,the entropy generation rate and exergy efficiency are analyzed to assess the energy utilization in the *** research findings indicate that,within the considered flow range,reducing the nozzle specific areaφfrom 0.03061 to 0.01083 can enhance the ejection coefficient by over 60.7%.This enhancement increases the air circulating rate,thereby intensifying convective heat transfer within the SAI ***,the reduction inφalso leads to a significant increase in the required bleed air pressure and a higher entropy generation rate,indicating lower exergy *** nozzle angleθnotably affects the distribution of hot and cold spots on the lip surface of the SAI ***θfrom 0°to 20°reduces the maximum temperature difference on the anti-icing chamber surface by 60 K.

关键词： Swirl anti-icing heat transfer exergy efficiency hot and cold spot aircraft engine

MICROCALORIMETRIC StuDIES OF SURFACE ACID/BASE PROPERTIES OF REDUCED IRON／MAGNESIUM CATALYSTS

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Chinese Journal of Catalysis 1996年第4期17卷 8-9页

作者：Ｔｕ　ＭａｉＳｈｅｎ　ＪｉａｎｙｉＣｈｅｎ　ＹｉＤｅｐａｒｔｍｅｎｔ　ｏｆ　ＣｈｅｍｉｓｔｒｙＮａｎｊｉｎｇ　Ｕｎｉｖｅｒｓｉｔｙ

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关键词： SURFACE ACID