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Effect of temperature and time on the precipitation ofκ-carbides in Fe-28Mn-10Al-0.8C low-density steels:Aging mechanism and its impact on material properties

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2189-2198页

作者： Yulin Gao Min Zhang Rui Wang Xinxin Zhang zhunli tan Xiaoyu Chong School of Mechanical Electronic and Control EngineeringMaterials Science and Engineering Research CenterBeijing Jiaotong UniversityBeijing 100044China Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China

In low-density steel,κ-carbides primarily precipitate in the form of nanoscale particles within austenite ***,their precipitation within ferrite matrix grains has not been comprehensively explored,and the second-phase evolution mechanism during aging remains *** this study,the crystallographic characteristics and morphological evolution ofκ-carbides in Fe-28Mn-10Al-0.8C(wt%)low-density steel at different aging temperatures and times and the impacts of these changes on the steels’microhardness and properties were comprehensively *** different heat treatment conditions,intragranularκ-carbides exhibited various morpho-logical and crystallographic characteristics,such as acicular,spherical,and short rod-like *** the initial stage of aging,acicularκ-carbides primarily precipitated,accompanied by a few spherical carbides.κ-Carbides grew and coarsened with aging time,the spherical carbides were considerably reduced,and rod-like carbides *** hardness testing demonstrated that the material’s hardness was affected by the volume fraction,morphology,and size ofκ-*** aging at higher temperatures led to an increase in carbide size and volume fraction,resulting in a gradual rise in *** deformation,the primary mechanisms for strengthening were dislocation strengthening and second-phase *** on these findings,potential strategies for improving material strength are proposed.

关键词： low-density steel κ-carbide solution-aging treatment hardness

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Tempering Behavior of Ductile 1700 MPa Mn-Si-Cr-C Steel Treated by Quenching and Partitioning Process Incorporating Bainite Formation

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Journal of Materials Science & Technology 2015年第2期31卷 199-204页

作者： Guhui Gao Han Zhang Xiaolu Gui zhunli tan Bingzhe Bai Materials Science & Engineering Research Center Beijing Jiaotong University Max-Planck-Institut für Eisenforschung Max-Planck-Str.1Düsseldorf 40237Germany Key Laboratory of Advanced Materials Department of Material Science & EngineeringTsinghua University

We obtained a good combination of strength and ductility in a 0.4C-2.0Mn-1.7Si-0.4Cr（wt%） steel,namely,;.7 GPa of ultimate tensile strength and;6% of elongation,by conducting a Q-P-T（quenching-partitioning- tempering） process incorporating the formation of carbide-free bainite. The tempering behavior of this steel was discussed by using experimental finding(scanning electron microscopy,X-ray diffraction（XRD）,transmission electron microscopy and dilatometer) and CCE（constrained carbon equilibrium） modeling. The XRD results combined with CCE calculation prove that carbon partitioning from martensite to austenite occurs during tempering. Consequently,the thermodynamic stability of retained austenite is enhanced. This idea can be utilized to design novel Q-P-T processes in future.

关键词： Bainite Quenching and partitioning Tempering Micro

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Analysis of the causes of the outer surface folding defects in N80-Q oil country tubular goods

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Baosteel Technical Research 2011年第1期5卷 56-59页

作者： PAN Dagang CAI Haiyan tan zhunli YU Jie Tube ＆ Pipe Technology Center Research Institute Baoshan Iron ＆ Steel Co. Ltd. Shanghai 201900 China

The causes to the outer surface folding defects in N80-Q oil country tubular goods （OCTG） were investigated through the observation of the defects＇ morphology, microstructure and the analysis of the chemical compositions. It is believed that the defect was resulted from the intrinsic flaws that originally existed on the billet; they were extended and oxidized during the following reheating and rolling processes. With more strict quality control and inspection of the billet, the defect can be prevented effectively from occurring.

关键词： OCTG defect rolling microstructure heat treatment

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Influence of ambient temperature on the CO_(2)emitted of light-duty vehicle

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Journal of Environmental Sciences 2024年第6期140卷 59-68页

作者： Dan tan Yachao Wang Jianwei tan Jiachen Li Changyu Wang Yunshan Ge School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

Because of global warming,people have paid more attention to greenhouse gas emitted by *** quantify the impact of temperature on vehicle CO_(2)emissions,this study was conducted using the world light vehicle test cycle on two light-duty E10 gasoline vehicles a ambient temperatures of-10,0,23,and 40℃,and found that CO_(2)emission factors of Vehicle1 in the low-speed phase were 22.07%and 20.22%higher than those of Vehicle 2 at cold star and hot start under-10℃.The reason was vehicle 1 had a larger displacement and more friction pairs than vehicle *** was the highest CO_(2)emission at the low-speed phase due to low average speed,frequent acceleration,and *** CO_(2)temperature factor and the ambient temperature had a strong linear correlation(R2=0.99).According to CO_(2)temperature factors and their relationships,CO_(2)emission factors of other ambien temperatures could be calculated when the CO_(2)emission factor of 23℃was obtained,and the method also could be used to obtain the CO_(2)temperature factors of different *** separate the effect of load setting and temperature variation on CO_(2)emission quantitatively a method was *** results showed that the load setting was dominant for the CO_(2)emission *** with 23℃,the CO_(2)emission for vehicle 1 caused by load setting variation were 62.83 and 47.42 g/km,respectively at-10 and 0℃,while those fo vehicle 2 were 45.01 and 35.63 g/km,respectively.

关键词： CO_(2)emission Ambient temperature E10 gasoline Light-duty vehicle WLTC

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Best Paper Award 2022

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Building Simulation 2024年第1期17卷 1-2页

作者： Gang tan College of Civil Engineering and Architecture Zhejiang University HangzhouZhejiang 310058China

I am pleased to announce that the following paper has been awarded the Best Review Paper 2022,which stands out from the 24 review papers published by Building Simulation from 2018(Volume 11)to 2022(Volume 15):Yuejing Zhao&Bin Zhao."Emissions of air pollutants from Chinese cooking:A literature review."Building Simulation,2018,11(5):977-995.

关键词： cooking stands award

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Preface to the Special Issue:AI Applications in Atmospheric and Oceanic Science:Pioneering the Future(Part I)

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Advances in Atmospheric Sciences 2024年第7期41卷 1279-1280页

作者： Zhemin tan Key Laboratory of Mesoscale Severe Weather Ministry of Educationand School of Atmospheric SciencesNanjing UniversityNanjing 210023China

As AI continues to establish itself as a cornerstone technology across various industries and scientific disciplines,its profound impact on atmospheric and oceanic science is becoming increasingly *** advantages of AI in surmounting obstacles within our field are undeniable,as evidenced by breakthroughs in weather forecasting(e.g.,Bi et al.,2023),climate prediction(e.g.,Ham et al.,2019),AI-based parameterization schemes(e.g.,Rasp et al.,2018;Wang and tan,2023),and *** the transformative potential of AI in atmospheric and oceanic science,this special issue endeavors to explore the extensive applications of AI in our domain.

关键词： weather forecasting prediction

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A Novel Extremum Seeking Control to Enhance Convergence and Robustness in the Presence of Nonlinear Dynamic Sensors

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Journal of Systems Science & Complexity 2024年第1期37卷 3-21页

作者： LIU Hengchang tan Ying OETOMO Denny School of Electrical Mechanical and Infrastructure EngineeringThe University of MelbourneParkville VIC 3010Australia

This paper focuses on optimizing an unknown cost function through extremum seeking(ES)control in the presence of a slow nonlinear dynamic sensor responsible for measuring the *** contrast to traditional perturbation-based ES control,which often suffers from sluggish convergence,the proposed method eliminates the time-scale separation between sensor dynamics and ES control by using the relative degree of the nonlinear sensor *** improve the convergence rate,the authors incorporate high-frequency dither signals and a *** enhance the robustness with the existence of rapid disturbances,an off-the-shelf linear high-gain differentiator is *** first result demonstrates that,for any desired convergence rate,with properly tuned parameters for the proposed ES algorithm,the input of the cost function can converge to an arbitrarily small neighborhood of the optimal solution,starting from any initial condition within any given compact ***,the second result shows the robustness of the proposed ES control in the presence of sufficiently fast,zero-mean periodic *** results substantiate these theoretical findings.

关键词： Averaging extremum seeking optimization singular perturbation time-scale separation

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Amorphous hybrid tungsten oxide–nickel hydroxide nanosheets used as a highly efficient electrocatalyst for hydrogen evolution reaction

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Nano Research 2024年第4期17卷 2499-2508页

作者： Chao Lyu Chenghai Dai Yiwei tan State Key Laboratory of Materials-Oriented Chemical Engineering School of Chemistry and Chemical EngineeringNanjing Tech UniversityNanjing 211816China

There are more challenges for alkaline hydrogen evolution reaction(HER)via simultaneously expediting the electron-coupled water dissociation process(Volmer step)and the following electrochemical H_(2) desorption(Heyrovsky step).Hybrid amorphous electrocatalysts are highly desirable for efficient hydrogen evolution from water-alkali electrolyzers due to the bifunctionality for the different elementary steps of HER and optimal interactions with water molecules and the reactive hydrogen intermediates(Had).Herein,the synthesis of amorphous hybrid ultrathin(tungsten oxide/nickel hydroxide)hydrate(a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O)nanosheets on nickel foam(NF)for efficient alkaline HER is *** structural and composition features of a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O are characterized in *** resulting a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O/NF electrocatalyst with the synergistic effect of both hybrid components for the HER elementary steps shows greatly improved the activity and durability for the HER with a low overpotential of-41 and-163 mV at-10 and-500 mA·cm^(-2),respectively,a Tafel slope as low as-72.9 mV·dec^(-1),and long-term stability of continuous electrolysis for at least 150 h accompanying by inappreciable overpotential change in 1 M *** the hybrid a-[WO_(3)/Ni(OH)_(2)]·0.2H_(2)O,Ni(OH)_(2) and WO_(3) moieties are separately responsible for accelerating dissociative adsorption of water and weakening Had adsorption strength,which is beneficial to the improvement of the alkaline HER activity.

关键词： amorphous nanomaterial bimetallic electrocatalyst tungsten oxide ultrathin nanosheet hydrogen evolution reaction

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An Improved Method for Approximating the Infinite-Horizon Value Function of the Discrete-Time Switched LQR Problem

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Journal of Systems Science & Complexity 2024年第1期37卷 22-39页

作者： HOU tan LI Yuanlong LIN Zongli Department of Automation Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of System Control and Information Processing Ministry of Education of ChinaShanghai 200240China Shanghai Engineering Research Center of Intelligent Control and Management Shanghai 200240China Charles L.Brown Department of Electrical and Computer Engineering University of VirginiaCharlottesvilleVA 22904-4743USA

This paper considers the problem of approximating the infinite-horizon value function of the discrete-time switched LQR *** particular,the authors propose a new value iteration method to generate a sequence of monotonically decreasing functions that converges exponentially to the value *** method facilitates us to use coarse approximations resulting from faster but less accurate algorithms for further value iteration,and thus,the proposed approach is capable of achieving a better approximation for a given computation time compared with the existing *** numerical examples are presented in this paper to illustrate the effectiveness of the proposed method.

关键词： Optimal control switched linear systems switched LQR problem.

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Mn-Si-Cr系无碳化物贝氏体/马氏体复相高强钢的研究进展

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材料导报 2017年第21期31卷 74-81页

作者：高古辉桂晓露谭谆礼白秉哲北京交通大学机械与电子控制工程学院材料中心北京100044

无碳化物贝氏体/马氏体复相高强钢具有比同等强度马氏体钢更优异的韧性和塑性,被广泛应用到轨道交通、机械、建筑等领域。文章概述了低成本Mn-Si-Cr系无碳化物贝氏体/马氏体复相钢近年来在合金化设计、工艺设计、微观组织、强韧化机理... 详细信息

无碳化物贝氏体/马氏体复相高强钢具有比同等强度马氏体钢更优异的韧性和塑性,被广泛应用到轨道交通、机械、建筑等领域。文章概述了低成本Mn-Si-Cr系无碳化物贝氏体/马氏体复相钢近年来在合金化设计、工艺设计、微观组织、强韧化机理、强塑化机理、延迟断裂及疲劳性能等方面取得的研究成果。特别介绍了近年来笔者在BQ&P工艺处理CFB/M复相钢方面的工作进展,经过BQ&P处理之后,CFB/M复相钢显示了更优异的强度、塑性、韧性和疲劳性能的匹配。最后简单介绍了Mn-Si-Cr系无碳化物贝氏体/马氏体复相钢在不同领域的应用情况,特别是其在重载高速铁路领域的应用现状和前景。

关键词：高强钢无碳化物贝氏体/马氏体复相组织强韧性疲劳性能 BQ&P工艺

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