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Macrosegregation and thermosolutal convection-induced freckle formation in dendritic mushy zone of directionally solidified Sn-Ni peritectic alloy

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Journal of Materials Science & Technology 2021年第16期75卷 21-26页

作者： Peng Peng Anqiao Zhang jinmian yue Xudong Zhang Yuanli Xu Institute of Materials Science and Engineering Lanzhou UniversityLanzhou730000China School of Physical Science and Technology Lanzhou UniversityLanzhou730000China

Compared with the growing applications of peritectic alloy,none research on the freckle formation during peritectic solidification has been reported before.Observation on the dendritic mushy zone of Sn-36 at.%Ni peritectic alloy during directional solidification at different growth velocities shows that the freckles are formed in two different regions:region I before peritectic reaction and region II after peritectic reaction.In addition,more freckles can be observed at lower growth velocities.Examination on the experimental results demonstrates that both the temperature gradient zone melting(TGZM)and Gibbs-Thomson(G–T)effects have obvious influences on the morphology of dendritic network during directional solidification.The current theories onKI Rayleigh number Racharacterizing the thermosolutal convection of dendritic mushy zone to predict freckle formation through the maximum of Ra can only explain the existence of region I while the appearance of region II after peritectic reaction cannot be predicted.Thus,a new Rayleigh number RaP is proposed in consideration of evolution of dendritic mushy zone by both effects and peritectic reaction.Theoretical prediction of RaPalso shows a maximum after peritectic reaction in addition to that before peritectic reaction,thus,agreeing well with the freckle formation in region II.In addition,more severe thermosolutal convection can be predicted by the new Rayleigh number RaP at lower growth velocities,which further demonstrates the reliability of RaP in describing the dependence of freckle formation on growth velocity.

关键词： Directional solidification Thermosolutal convection Dendritic solidification Peritectic microstructures

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Analysis on fluid permeability of dendritic mushy zone during peritectic solidification in a temperature gradient

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Journal of Materials Science & Technology 2021年第12期71卷 169-176页

作者： Peng Peng jinmian yue Anqiao Zhang Xudong Zhang Yuanli Xu Institute of Materials Science and Engineering Lanzhou UniversityLanzhou730000China School of Physical Science and Technology Lanzhou UniversityLanzhou730000China

Compared with the growing applications of peritectic alloys,none research on the fluid permeability K of dendritic network during peritectic solidification has been reported before.The fluid permeability K of dendritic network in the mushy zone during directional solidification of Sn-Ni peritectic alloy was investigated in this study.Examination on the experimental results demonstrates that both the temperature gradient zone melting(TGZM)and Gibbs-Thomson(G–T)effects have obvious influences on the morphology of dendritic network during directional solidification.This is realized through different stages of liquid diffusion within dendritic mushy zone by these effects during directional solidification.The TGZM effect is demonstrated to play a more important role as compared with the G–T effect during directional solidification.Besides,it is shown that the evolution of dendrite network is more complex during peritectic solidification due to the involvement of the peritectic phase.Through the specific surface SV,analytical expression based on the Carman–Kozeny model was proposed to analyze the fluid permeability of dendritic mushy zone in directionally solidified peritectic alloys.In addition,it is interesting to find a rise in permeability K after peritectic reaction in both theoretical predication and experimental results,which is different from that in other alloys.The theoretical predictions show that this rise in fluid permeability K after peritectic reaction is caused by the remelting/resolidification process on dendritic structure by the TGZM and G–T effects during peritectic solidification.

关键词： Alloys Diffusion behaviour Directional solidification Peritecticm icrostructures Solid/liquid interface

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Diffusion-induced abnormal tertiary dendrite during peritectic solidification in a temperature gradient

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Journal of Materials Science & Technology 2021年第13期72卷 197-201页

作者： Peng Peng Anqiao Zhang jinmian yue Xudong Zhang Yuanli Xu Institute of Materials Science and Engineering Lanzhou UniversityLanzhou 730000China School of Physical Science and Technology Lanzhou UniversityLanzhou 730000China

1.Introduction Dendritic structure are commonly encountered during solidification[1-4],especially in systems freezing with relatively low entropies of transformation[1,5].Generally speaking,the dendritic structure is composed of primary dendrite stem,secondary branch and even tertiary and higher order dendrite arms[1].Different kinds of models have been proposed for describing the growth of primary dendrite[1-5]and secondary dendrite arms[1,6,7].

关键词： solidification transformation Diffusion

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Investigation on peritectic solidification in Sn-Ni peritectic alloys through in-situ observation

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Journal of Materials Science & Technology 2021年第31期90卷 236-242页

作者： Peng Peng Anqiao Zhang jinmian yue Shengyuan Li Wanchao Zheng Li Lu School of Physical Science and Technology Lanzhou UniversityLanzhou 730000China School of Physics and Electronic Information Engineering Qinghai Normal UniversityXining753000China

The solidification of Sn-Ni peritectic alloys in which both the primary Ni_(3)Sn_(2)and peritectic Ni_(3)Sn_(4)phases were intermetallic compound phases(IMCs)with narrow solubility ranges was investigated through confocal laser scanning microscope.Analysis on the interface migration at different cooling rates shows that the rate of peritectic reaction is much smaller than previous reports,and the growth of peritectic phase is mainly attributed to direct precipitation from the melt in Sn-Ni alloy after peritectic reaction.In addition,different from other peritectic alloys where the solidified phases are solid solution phases,the"step"growth of both Ni_(3)Sn_(2)and Ni_(3)Sn_(4)phases was observed.The dependences of the step thickness on both the cooling rate and solidification time were measured,which shows that the step thicknesses of both phases gradually decrease as solidification proceeds.This was confirmed to be attributed to the difference between the actual and equilibrium melt concentrations during solidification.In addition,the increase of the normal growth velocity of Ni_(3)Sn_(4)phase with increasing cooling rate was also proved through both the experimental observation and quantitative prediction.

关键词： Peritectic solidification Solidification microstructure Image analysis Alloys Microstructure

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数字经济发展赋能绿色经济增长:后发优势与隧道效应

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统计与决策 2024年第1期40卷 23-28页

作者：白雄韩锦绵张文瑞西北大学中国西部经济发展研究院西安710127 西北大学经济管理学院西安710127 西安欧亚学院金融与数据科学学院西安710065

文章测算了我国281个地级及以上城市数字经济发展综合指数和基于碳排放效率的绿色经济增长指数,并从技术进步角度分析和探究数字经济赋能绿色经济增长的机制,从相对差距的视角论证数字化程度较低的城市发展数字经济的驱动因素及后发优... 详细信息

文章测算了我国281个地级及以上城市数字经济发展综合指数和基于碳排放效率的绿色经济增长指数,并从技术进步角度分析和探究数字经济赋能绿色经济增长的机制,从相对差距的视角论证数字化程度较低的城市发展数字经济的驱动因素及后发优势。研究发现:(1)数字经济能够显著地促进绿色经济增长,是提升碳排放效率、助力高质量发展的重要因素;(2)数字经济能够通过促进技术进步赋能绿色经济增长;(3)数字经济在相对落后的城市存在后发优势,发展数字经济是缩小城市差距、实现区域协调的重要手段;(4)在数字经济发展相对落后的城市中存在隧道效应,该效应是相对落后城市发展数字经济的关键因素。

关键词：数字经济绿色经济增长后发优势隧道效应

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A heuristic control framework for heavy-duty hexapod robot over complex terrain

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IET Cyber-Systems and Robotics 2022年第4期4卷 322-330页

作者： jinmian Hou Hui Chai Yibin Li Yaxian Xin Wei Chen School of Control Science and Engineering Shandong UniversityJinanChina Engineering Research Center of Intelligent Unmanned System Ministry of EducationShandong UniversityJinanChina

The large and heavy-duty hexapod robot has strong motion stability and load capacity,which promises to have a wide range of application prospects in rescue and disaster relief.Multi-mode gait and static stability during walking make the hexapod robot adapt to more diverse terrains,while little research has been conducted on the motion control methods of heavy-duty hexapod robots in complex environments.A novel heuristic whole-body motion control framework for the heavy-duty hexapod robot to traverse complex terrain is presented.By splitting the legged locomotion into a single task,the whole-body motion could be planned in a reasonable time.The terrain adaptation strategy is designed to improve the complex terrain passability.Ground reaction forces are then optimised based on single rigid-body dynamics with heuristics.This framework utilised simple but powerful heuristics to approximate complex dynamics and allows for a single set of parameters for all task conditions.Simulation results demonstrate the robustness and adaptability of the proposed framework.

关键词： legged locomotion robotics robots

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容量目标通气与高频振荡通气治疗新生儿呼吸窘迫综合征的效果比较

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中国医学创新 2024年第5期21卷 28-31页

作者：陈进勉陈伟成唐荔蔡文双湛江市妇幼保健计划生育服务中心新生儿科广东湛江524000

目的:对比研究容量目标通气、高频振荡通气两种模式在新生儿呼吸窘迫综合征中的治疗效果。方法:随机将2021年6月—2023年6月在湛江市妇幼保健计划生育服务中心治疗的新生儿呼吸窘迫综合征患儿100例分为对照组与研究组,每组50例。研究组... 详细信息

目的:对比研究容量目标通气、高频振荡通气两种模式在新生儿呼吸窘迫综合征中的治疗效果。方法:随机将2021年6月—2023年6月在湛江市妇幼保健计划生育服务中心治疗的新生儿呼吸窘迫综合征患儿100例分为对照组与研究组,每组50例。研究组采取高频振荡通气模式(高频机械通气+目标潮气量),对照组采取容量目标通气模式。对比两组动脉血气指标、并发症发生率、死亡率、有创通气时间、氧疗时间、住院时间。结果:研究组有创通气时间、氧疗时间、住院时间均短于对照组(P0.05)。干预前两组血氧分压、血氧饱和度、pH值、二氧化碳分压比较,差异均无统计学意义(P>0.05);干预48 h后,研究组的血氧分压、血氧饱和度、pH值较干预前和对照组均更高,二氧化碳分压较干预前和对照组更低(P<0.05)。研究组的并发症发生率(10.00%)低于对照组(36.96%)(P<0.05)。结论:高频振荡通气模式可以更有效地改善新生儿呼吸窘迫综合征患儿动脉血气指标,缩短康复时间,减少各类并发症出现。

关键词：容量目标通气高频振荡通气新生儿呼吸窘迫综合征

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A survey of the development of quadruped robots: Joint configuration, dynamic locomotion control method and mobile manipulation approach

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Biomimetic Intelligence & Robotics 2022年第1期2卷 9-21页

作者： Hui Chai Yibin Li Rui Song Guoteng Zhang Qin Zhang Song Liu jinmian Hou Yaxian Xin Ming Yuan Guoxuan Zhang Zhiyuan Yang School of Control Science and Enginering Shandong University Jinan 250061China Engineering Research Center of Ielligent Urumarned System Muristry of EducationrShandong UniversityJinan 250061China School of Elecrical Engineering.University of Jinan Jinan 250022China

Some quadruped robots developed recently show better dynamic performance and environmental adaptability than ever, and have been preliminarily applied in the field of emergency disposal, military reconnaissance and infrastructure construction. The development route, mechanisms design, control methods and mobile manipulating approaches of the quadruped robots are surveyed in this article. Firstly, the development route of the quadruped robot is combed, as the references of the forecast of the future work on quadruped robots. Then the bionic structure and the motion control method of the quadruped robot is summarized, the advantages and disadvantages are analyzed in aspects of gait switching, terrain adaption and disturbance resistance. Subsequently, aiming at the mobile manipulation of the quadruped robot, the representative leg-arm collaborative robots and the multi-task-oriented Whole-body Control (WBC) methods are introduced. Finally, the summary and future work of the quadruped robots is given.

关键词： Quadruped robot Joint configuration Dynamic locomotion control Mobile manipulation Hyper-bio-inspired mechanism design

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电炉氧化法冶炼低硼含量车轮钢的技术探讨

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山西冶金 2023年第5期46卷 26-28,46页

作者：李伟岳锦绵山西太钢不锈钢股份有限公司山西太原030003

有关热力学计算和实验结果表明,精炼过程不具备脱硼条件,电炉采用w(Si)≤0.45%、w(B)≤8×10^(-6)的铁水,以及低硼含量原辅料,按常规工艺能够生产w(B)≤5×10^(-6)的车轮钢。为更好地提升车轮钢质量,通过对电炉氧化法冶炼低硼含量车轮... 详细信息

有关热力学计算和实验结果表明,精炼过程不具备脱硼条件,电炉采用w(Si)≤0.45%、w(B)≤8×10^(-6)的铁水,以及低硼含量原辅料,按常规工艺能够生产w(B)≤5×10^(-6)的车轮钢。为更好地提升车轮钢质量,通过对电炉氧化法冶炼低硼含量车轮钢技术进行探讨,提出以高硅高硼铁水为原料的电炉氧化法冶炼低硼含量钢工艺,通过采取低拉碳脱硼、兑铁水配碳控制钢水终点氧化性等措施,可实现w(B)≤3×10^(-6)高品质洁净钢的生产。

关键词：车轮钢低硼氧化法洁净钢

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Detecting anomalies in vector boson scattering

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Chinese Physics C 2021年第7期45卷 51-64页

作者：李金勉杨硕张饶 College of Physics Sichuan UniversityChengdu 610065China Department of Physics Liaoning Normal UniversityDalian 116029China Department of Physics Dalian UniversityDalian 116622China

Measuring vector boson scattering(VBS)precisely is an important step toward understanding the electroweak symmetry breaking of and detecting new physics beyond the standard model(SM).Herein,we propose a neural network that compresses the features of the VBS data into a three-dimensional latent space.The consistency of the SM predictions and experimental data is tested via binned log-likelihood analysis in the latent space.We show that the network is capable of distinguishing different polarization modes of WWjj production in both di-and semileptonic channels.The method is also applied to constrain the effective field theory and two Higgs Doublet Model.The results demonstrate that the method is sensitive to general new physics contributing to the VBS.

关键词： LHC electroweak symmetry breaking Higgs boson machine learning

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