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Microstructure evolution and strengthening mechanism of high -performance powder metallurgy TA15 titanium alloy by hot rolling

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1426-1436页

作者： Ying Gao Ce Zhang Jiazhen Zhang Xin Lu Beijing Advanced Innovation center for Materials Genome engineering State Key Laboratory for Advanced Metals and MaterialsInstitute for Advanced Ma-terials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China National engineering research center for Advanced Rolling technology National Engineering Research Center for Flat Rolling EquipmentInstitute of Engin-eering TechnologyUniversity of Science and Technology BeijingBeijing 100083China

Hot deformation of sintered billets by powder metallurgy(PM)is an effective preparation technique for titanium alloys,which is more significant for high-alloying *** this study,Ti–6.5Al–2Zr–Mo–V(TA15)titanium alloy plates were prepared by cold press-ing sintering combined with high-temperature hot *** microstructure and mechanical properties under different process paramet-ers were *** microscope,electron backscatter diffraction,and others were applied to characterize the microstructure evolution and mechanical properties strengthening *** results showed that the chemical compositions were uniformly dif-fused without segregation during sintering,and the closing of the matrix craters was accelerated by increasing the sintering *** block was hot rolled at 1200℃ with an 80%reduction under only two passes without *** strength and elongation of the plate at 20–25℃ after solution and aging were 1247 MPa and 14.0%,respectively,which were increased by 24.5%and 40.0%,respect-ively,compared with the as-sintered alloy at 1300℃.The microstructure was significantly refined by continuous dynamic recrystalliza-tion,which was completed by the rotation and dislocation absorption of the substructure surrounded by low-angle grain *** hot rolling combined with heat treatment,the strength and plasticity of PM-TA15 were significantly improved,which resulted from the dense,uniform,and fine recrystallization structure and the synergistic effect of multiple slip systems.

关键词： elemental powder powder metallurgy titanium alloy hot rolling strength and plasticity

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Near-field wideband beam training for ELAA with uniform circular array

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Science China(Information Sciences) 2024年第6期67卷 370-383页

作者： Yuhao CHEN Linglong DAI Department of Electronic engineering Tsinghua UniversityBeijing National Research Center for Information Science and Technology (BNRist)

Extremely large-scale antenna array(ELAA) at millimeter wave(mmWave) and Terahertz(THz)band has been considered a key technology for combating high attenuation in high-frequency bands in future6G communications. Uniform circular arrays(UCAs) have attracted much attention because of their ability to provide flat beamforming gain at all angles. To realize efficient beamforming, beam training is widely used to acquire channel state information. However, with a large antenna number, the beam training overhead in ELAA systems becomes overwhelming. Moreover, with a large bandwidth, the beam defocus effect severely degrades beam training accuracy. To address these issues, this paper proposes a frequency-dependent focusing(FDF)-based beam training scheme to realize effective beam training in near-field wideband ELAA systems with UCA. Specifically, we first analyze the FDF property of UCA, where signals at different subcarriers can simultaneously focus on different distances. Then, by exploiting the FDF property to search different distances using different subcarriers simultaneously, we design a hierarchical codebook and propose an FDFbased beam training scheme. To reveal the effectiveness of the proposed scheme, we compare its necessary beam training overhead with that of existing schemes. Finally, the simulation results demonstrate that the proposed scheme can achieve accurate beam training in near-field wideband UCA systems with a low beam training overhead.

关键词： extremely large-scale antenna array (ELAA) uniform circular array (UCA) near-field wideband beam training

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Constructing S-scheme charge separation in cobalt phthalocyanine/oxygen-doped g-C_(3)N_(4) heterojunction with enhanced photothermal-assisted photocatalytic H_(2) evolution

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Rare Metals 2024年第1期43卷 198-211页

作者： Wei-Long Shi Zheng Xu Yu-Xing Shi Ling-Ling Li Jia-Lin Lu Xin-Hai Sun Xin Du Feng Guo Chang-Yu Lu School of Material Science and engineering Jiangsu University of Science and TechnologyZhenjiang 212003China School of Energy and Power Jiangsu University of Science and TechnologyZhenjiang 212003JiangsuChina College of Chemistry Zhengzhou UniversityZhengzhou 450001China School of Water Resource and Environment Hebei Province Key Laboratory of Sustained Utilization and Development of Water RecourseHebei Center for Ecological and Environmental Geology ResearchHebei Geo UniversityShijiazhuang 050031China

Hydrogen acquisition from solar energy is an effective way to address energy crisis,which makes the development of efficient photocatalysts become the main direction of scientific ***,cobalt phthalocyanine/oxygen-doped g-C_(3)N_(4)(CoPc/OCN) S-scheme heterojunction photocatalyst was designed by coupling multi-step calcination with solvothermal method for enhanced photothermal-assisted photocatalytic H_(2) *** multistep calcined g-C_(3)N_(4) is easier for O-doping formation,and the ethanol solvothermal strategy is utilized to enhance the dispersion of CoPc on OCN nano sheet surface and forms sufficient S-scheme heterojunction through *** addition,the active sites and excellent photothermal properties of CoPc itself further improve the integrated photocatalytic activity of CoPc/OCN S-scheme *** optimal photocatalytic hydrogen evolution rate of CoPc/OCN S-scheme heterojunction photocatalyst reached 9.56 mmol·g^(-1)·h^(-1),which is 2.69 and 1.23 times higher than that of CN and OCN,*** work provides a valuable design idea and scheme for enhancing the multi-factor co-assisted photocatalytic H_(2) evolution performance.

关键词： Photothermal Photocatalytic H_(2)evolution Cobalt phthalocyanine Oxygen-doped g-C_(3)N_(4) Sscheme heterojunction

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Effect of nucleating agents on the electrical properties of cross-linked polyethylene under tensile stress

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High Voltage 2024年第2期9卷 429-439页

作者： Yunqi Xing Jiahao Liu Jingang Su Junwei Zha Guochang Li Ze Guo Xiaozhen Zhao Mengjia Feng State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of TechnologyTianjinChina Electric Power research Institute of State Grid hebei Electric Power Supply Co. Ltd.ShijiazhuangChina Beijing Advanced Innovation center for Materials Genome engineering School of Chemistry and Biological EngineeringUniversity of Science&Technology BeijingBeijingChina Institute of Advanced Electrical Materials Qingdao University of Science and TechnologyQingdaoChina

During the operation of high-voltage cables,external stress and residual stress can affect the aggregated structure of insulating materials and lead to significant deterioration in their electrical *** investigate the evolution characteristics of the electrical properties of cross-linked polyethylene(XLPE)under mechanical stress,this paper ex-plains the relationship between the aggregated structure of XLPE and its electrical properties and proposes a method for improving insulation performance under me-chanical *** results show that metallocene polyethylene used as a nucleating agent can promote crystallisation through heterogeneous nucleation and increase Young's modulus by non-uniform nucleation,increasing crystallinity and reducing interplanar spacing,resulting in more complete crystal forms and reduced damage to the aggregated structure during the tensile *** nucleating agent modification,the XLPE crystallisation becomes more uniform,and interfacial adhesion forces *** weakened interface damage process between the amorphous and crystalline regions under tensile stress effectively inhibits the process of molecular chain polarisation turning and reduces trap *** modified XLPE crystal structure shows a tendency towards densification and enhanced molecular chain interactions,which can reduce the damage to the aggregated structure under tensile stress,while the reduced free volume inside the material and the shortened average free path of carriers can weaken the damage of high-energy electrons to molecular chains,thereby inhibiting the process of electrical tree *** results show that nucleating agents have great potential for maintaining the stable operation of XLPE cables under mechanical stress.

关键词： stress electrical damage

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Effect of lanthanum on inclusions in non-oriented electrical steel slabs

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Journal of Iron and Steel research International 2024年第7期31卷 1680-1691页

作者： Qiang Ren Zhi-yuan Hu Yun-xia Liu Wei-cheng Zhang Zi-qi Gao Li-feng Zhang School of Mechanical engineering Yanshan UniversityQinhuangdao 066004HebeiChina School of Metallurgical and Ecological engineering University of Science and Technology BeijingBeijing 100083China research and Development Department Shougang Zhixin Qian'an Electromagnetic Material Co.Ltd.Qian'an 064400HebeiChina School of Mechanical and Materials engineering North China University of TechnologyBeijing 100144China

The effect of lanthanum on the characteristics of inclusions in the slab of non-oriented electrical steels was investigated through industrial trials and thermodynamic *** number,size,and chemical composition of inclusions in the surface,one-quarter of thickness and the center of slabs with and without lanthanum addition were statistically analyzed using an automatic inclusion analysis *** the lanthanum-free slab,inclusions were predominately ***_(2)O_(3),MgO,and AlN as well as a small number of Al_(2)O_(3)-MgO-CaO and *** number densities of oxide inclusions and AlN decreased from the surface to the center of the slab,which was ascribed to the difference in cooling intensity during the continuous *** the steel with lanthanum addition,inclusions were modified into LaAlO_(3) and La_(2)O_(2)S and gradually transformed into dual-phase MgO-La_(2)S3 with an increasing distance from the slab surface due to the reaction between the lanthanum-containing inclusion and the steel *** uneven distribution of oxide inclusions along the thickness of the slab was eliminated in the lanthanum-bearing slab because the dissolved oxygen was remarkably decreased by ***-bearing inclusions were more likely to agglomerate AlN by inducing the heterogeneous nucleation of AlN on their surface,while small-size ***_(2)O_(3) inclusions hardly showed a coarsening effect on the size of AlN.

关键词： Lanthanum-Inclusion Non-oriented electrical steel Aluminum nitride Heterogenous nucleation

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Observation of an upward lightning flash with 21 upward positive leaders initiated from different wind turbines in wind farm

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High Voltage 2024年第1期9卷 163-171页

作者： Li Cai Yifeng Ke Wenchao Fan Ruisheng Yan Mi Zhou Jianguo Wang Yadong Fan engineering research center of Ministry of Education for Lightning Protection and Grounding technology School of Electrical Engineering and AutomationWuhan UniversityWuhanChina

As the wind turbine height increases,the probability of multiple upward leaders flashes within the wind farm *** this study,an upward lightning flash containing 21 upward positive leaders(UPLs)initiated from different wind turbines in Zhangbei Wind Farm was *** average speed of the UPLs was 1.2×10^(5) m/s,which mostly decreased to zero before reaching the cloud *** four UPLs developed to cloud height,with prolonged periods of bright light on three of them and with a minimum duration of 126 ms.A total of nine return strokes occurred on the other two dissipated leader channels,and the numbers of strokes on the two channels was six and three,*** average interstroke interval for the return strokes was 10.5 *** of these nine return strokes had peak currents smaller than 10 *** high-speed video frames confirmed that competition does exist between the UPLs,and the range of shielding effects increases as the height of the ULs *** effect of fan rotation on the initiation of upward leaders and the shielding effect between the wind turbines and upward leaders are discussed.

关键词： flash return initiated

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Effect of oxide inclusions on MnS precipitates and tensile mechanical property of high-strength low-alloy steel

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Journal of Iron and Steel research International 2024年第5期31卷 1210-1220页

作者： Xiao-yong Gao Hong Wei Li-feng Zhang School of Mechanical engineering Yanshan UniversityQinhuangdao066004HebeiChina School of Materials Science and engineering Yanshan UniversityQinhuangdao066004HebeiChina School of Mechanical and Materials engineering North China University of TechnologyBeijing100144China

The key role of oxide inclusions on the microstructure and mechanical property of a high-strength low-alloy steel was *** field emission scanning electron microscope equipped with energy-dispersive spectrometry was used to characterize MnS *** inclusions play an important role in the shape control of MnS *** oxides fovored to decrease the size and the aspect ratio of MnS *** less oxide inclusions in the steel,approximately over 16.7%MnS precipitates were with aspect ratio a>5 and pure MnS precipitates accounted for 75.9%in ***,with more oxide inclusions in the steel,only 7.4%MnS precipitates were with a>5 and pure MnS precipitates accounted for 60.1%in *** of MnS by oxide inclusions improved the strength and inhibited the *** oxide inclusions in the steel increased the yield strength and tensile strength of the steel in both longitudinal and transverse directions,and lowered the anisotropy of the mechanical property.

关键词： High-strength low-alloy steel MnS Oxide inclusion Mechanical property Anisotropy

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Hybrid structure of iron single atoms and metallic titanium for photothermal ethanol steam reforming

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Science China Chemistry 2024年第3期67卷 848-854页

作者： Dachao Yuan Guanda Han Zhixuan Wang Jianguo Zhao Kailuan Li Pengfei Wang Jianjun Hao Yaguang Li Jinhua Ye College of Mechanical and Electrical engineering Technology Innovation Center of Intelligent Agricultural EquipmentHebei Agricultural UniversityBaoding 071001China research center for Solar Driven Carbon Neutrality The College of Physics Science and TechnologyInstitute of Life Science and Green DevelopmentHebei UniversityBaoding 071002China International center for Materials Nanoarchitectonics(WPI-MANA) National Institute for Materials Science(NIMS)1-1 NamikiTsukubaIbaraki 305-0044Japan Graduate School of Chemical Science and engineering Hokkaido UniversitySapporo 060-0814Japan

Photothermal ethanol steam reforming(ESR) is currently limited by low intrinsic activity and strong solar energy ***,we synthesized Fe single atoms supported on CeO_(2)(SA Fe-CeO_(2)) to exhibit excellent low-temperature ESR activity with a hydrogen production rate of 512 mmol g^(-1)h^(-1) at 350℃,becuase of the high oxidation state of Fe single atoms to weaken the reaction barrier of ethanol ***,a heterostructure of SA Fe-CeO_(2) and Ti foil could eliminate 66% of infrared radiation via the size effect,thus achieving a 3.5 sun-driven temperature of 347℃.Consequently,the heterostructure of SA Fe-CeO_(2) and Ti foil shows a hydrogen generation rate of 984 mmol g^(-1)h^(-1) of ESR and 11.31% of solar-to-hydrogen energy conversion efficiency,which outperforms other photothermal ethanol-hydrogen production *** study provides a new path for designing active catalytic sites and trapping light energy of photothermal catalysts.

关键词： photothermal catalysis single atoms heterostructure ethanol steam reforming iron

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Next‑Generation Green Hydrogen: Progress and Perspective from Electricity, Catalyst to Electrolyte in Electrocatalytic Water Splitting

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Nano-Micro Letters 2024年第11期16卷 274-322页

作者： Xueqing Gao Yutong Chen Yujun Wang Luyao Zhao Xingyuan Zhao Juan Du Haixia Wu Aibing Chen College of Chemical and Pharmaceutical engineering Hebei University of Science and TechnologyShijiazhuang 050018People’s Republic of China

Green hydrogen from electrolysis of water has attracted widespread attention as a renewable power *** several hydrogen production methods,it has become the most promising ***,there is no large-scale renewable hydrogen production system currently that can compete with conventional fossil fuel hydrogen *** energy electrocatalytic water splitting is an ideal production technology with environmental cleanliness protection and good hydrogen purity,which meet the requirements of future *** review summarizes and introduces the current status of hydrogen production by water splitting from three aspects:electricity,catalyst and *** particular,the present situation and the latest progress of the key sources of power,catalytic materials and electrolyzers for electrocatalytic water splitting are ***,the problems of hydrogen generation from electrolytic water splitting and directions of next-generation green hydrogen in the future are discussed and *** is expected that this review will have an important impact on the field of hydrogen production from water.

关键词： Hydrogen Electrolysis Hydrogen production Renewable energy Catalyst

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Influence of syngas components and ash particles on the radiative heat transfer in a radiant syngas cooler

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Chinese Journal of Chemical engineering 2024年第4期68卷 203-215页

作者： Chen Han Youmin Situ Huaxing Zhu Jianliang Xu Zhenghua Dai Guangsuo Yu Haifeng Liu National Energy Coal Gasification technology research and Development center East China University of Science and TechnologyShanghai 200237China Shanghai engineering research center of Coal Gasification East China University of Science and TechnologyShanghai 200237China

Radiant syngas cooler(RSC)is widely used as a waste heat recovery equipment in industrial *** this work,an RSC with radiation screens is established and the impact of gaseous radiative property models,gas components,and ash particles on heat transfer is investigated by the numerical simulation *** the syngas components and the pressure environment of the RSC,a modified weighted-sum-of-gray-gases model was *** modified model shows high accuracy in *** computational fluid dynamics simulation,the calculated steam production is only 0.63%in error with the industrial *** with Smith's model,the temperature decay along the axial direction calculated by the modified model is *** components are of great significance to heat recovery capacity,especially when the absorbing gas fraction is less than 10%.After considering the influence of particles,the outlet temperature and the proportion of radiative heat transfer are less affected,but the difference in steam output reaches 2.7 t·h^(-1).The particle deposition on the wall greatly reduces the heat recovery performance of an RSC.

关键词： Radiant syngas cooler Weighted-sum-of-gray-gases model Numerical simulation Particle radiation

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