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Significant annealing-induced hardening effect in nanolaminate d-nanotwinne d(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)me dium-entropy alloy by severe cold rolling

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Journal of Materials Science & Technology 2024年第3期170卷 156-166页

作者： Shuqing Yuan Hui Fu lei qian Chi Fai Cheung Xu-Sheng Yang State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen 518060China

Due to the easy coarsening caused by poor thermal stability,the verified annealing-induced hardening in nanograined metals can only maintain at a relatively low-temperature range.In this study,a nanolam-inated(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8)medium-entropy alloy with an average lamellae thickness of∼20 nm embedded by thinner nanotwins was fabricated by severe cold rolling to achieve superior thermal stability.Compared with the conventional nanotwinned CrCoNi with nanotwins inside ultra-fined grains,the hier-archical nanolaminated-nanotwinned(CrCoNi)_(97.4)Al_(0.8)Ti_(1.8) exhibits a significant annealing-induced hard-ening effect,i.e.,hardness increasing from∼250 HV in the original specimen to∼500 HV in the cold-rolled status and finally∼630 HV after annealing at 600℃for 1 h.Detailed microstructure characterizations reveal that the reduced dislocation density and formation of L1_(2)ordered domain are mainly responsible for such hardening effect,which is facilitated by the effectively suppressed coarsening with annealing temperature,i.e.,slow detwinning process and well-retained low-angle nanolamellar structure.The coarsening mechanisms from the cold-rolled nanolamellae to the fully recrystallized micro-equiaxed structures under the annealing temperatures ranging from 400 to 800℃ were also elucidated by atomic observations.

关键词： Annealing-induced hardening Thermal stability Nanolaminated-nanotwinned structure CrCoNi Detwinning Grain boundary migration

The FAST all sky HI survey(FASHI):The first release of catalog

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 112-133页

作者： Chuan-Peng Zhang Ming Zhu Peng Jiang Cheng Cheng Jing Wang Jie Wang Jin-Long Xu Xiao-Lan Liu Nai-Ping Yu lei qian Haiyang Yu Mei Ai Yingjie Jing Chen Xu Ziming Liu Xin Guan Chun Sun Qingliang Yang Menglin Huang Qiaoli Hao FAST Collaboration Guizhou Radio Astronomical Observatory Guizhou UniversityGuiyang 550000China National Astronomical Observatories Chinese Academy of Sciences(CAS)Beijing 100101China Chinese Academy of Sciences South America Center for Astronomy National Astronomical ObservatoriesCASBeijing 100101China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China

The FAST All Sky HI survey(FASHI)was designed to cover the entire sky observable by the Five-hundred-meter Aperture Spherical radio Telescope(FAST),spanning approximately 22000 square degrees of declination between-14°and+66°,and in the frequency range of 1050-1450 MHz,with the expectation of eventually detecting more than 100000 HI sources.Between August 2020 and June 2023,FASHI had covered more than 7600 square degrees,which is approximately 35%of the total sky observable by FAST.It has a median detection sensitivity of around 0.76 m Jy beam-1and a spectral line velocity resolution of~6.4 km s-1at a frequency of~1.4 GHz.As of now,a total of 41741 extragalactic HI sources have been detected in the frequency range 1305.5-1419.5 MHz,corresponding to a redshift limit of z■0.09.By cross-matching FASHI sources with the Siena Galaxy Atlas(SGA)and the Sloan Digital Sky Survey(SDSS)catalogs,we found that 16972(40.7%)sources have spectroscopic redshifts and 10975(26.3%)sources have only photometric redshifts.Most of the remaining 13794(33.0%)HI sources are located in the direction of the Galactic plane,making their optical counterparts difficult to identify due to high extinction or high contamination of Galactic stellar sources.Based on current survey results,the FASHI survey is an unprecedented blind extragalactic H I survey.It has higher spectral and spatial resolution and broader coverage than the Arecibo Legacy Fast ALFA Survey(ALFALFA).When completed,FASHI will provide the largest extragalactic HI catalog and an objective view of HI content and large-scale structure in the local universe.

关键词： surveys redshifts galaxies telescope radio lines HI line

Prescribed-Time Fully Distributed Nash Equilibrium Seeking Strategy in Networked Games

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IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 261-263页

作者： Cheng qian lei Ding the Institute of Advanced Technology for Carbon Neutrality College of Automation&the College of Artificial Intelligence Nanjing University of Posts and TelecommunicationsNanjing 210023China IEEE

Dear Editor, This letter is concerned with prescribed-time fully distributed Nash equilibrium seeking for networked games under directed graphs. An adaptive algorithm is proposed to ensure the convergence of all players to the Nash equilibrium without requiring any knowledge of global parameters. Moreover, it is theoretically proved that the convergence time of the proposed seeking strategy can be predefined based on practical requirements. Finally, a numerical example is presented to validate the effectiveness of the proposed method.

关键词： parameters seeking prescribed

Toward a rapid and convenient nanoplastic quantification method in laboratory-scale study based on fluorescence intensity

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Frontiers of Environmental Science & Engineering 2024年第5期18卷 117-126页

作者： Ruiqi Yan Sen Lin qian Ding lei Zhang Xia Yu Wentao Zhao qian Sui State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process School of Resources and Environmental EngineeringEast China University of Science and TechnologyShanghai200237China State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and EngineeringTongji UniversityShanghai200092China Shanghai Institute of Pollution Control and Ecological Security Shanghai200092China

The thorough investigation of nanoplastics(NPs)in aqueous environments requires efficient and expeditious quantitative analytical methods that are sensitive to environmentally relevant NP concentrations and convenient to employ.Optical analysis-based quantitative methods have been acknowledged as effective and rapid approaches for quantifying NP concentrations in laboratory-scale studies.Herein,we compared three commonly used optical response indicators,namely fluorescence intensity(FI),ultraviolet absorbance,and turbidity,to assess their performance in quantifying NPs.Furthermore,orthogonal experiments were conducted to evaluate the influence of various water quality parameters on the preferred indicator-based quantification method.The results revealed that FI exhibits the highest correlation coefficient(>0.99)with NP concentration.Notably,the limit of quantification(LOQ)for various types of NPs is exceptionally low,ranging from 0.0089 to 0.0584 mg/L in ultrapure water,well below environmentally relevant concentrations.Despite variations in water quality parameters such as pH,salinity,suspended solids(SS),and humic acid,a robust relationship between detectable FI and NP concentration was identified.However,an increased matrix,especially SS in water samples,results in an enhanced LOQ for NPs.Nevertheless,the quantitative method remains applicable in real water bodies,especially in drinking water,with NP LOQ as low as 0.0157–0.0711 mg/L.This exceeds the previously reported detectable concentration for 100 nm NPs at 40µg/mL using surface-enhanced Raman spectroscopy.This study confirms the potential of FI as a reliable indicator for the rapid quantification of NPs in aqueous environments,offering substantial advantages in terms of both convenience and cost-effectiveness.

关键词： Nanoplastic quantification Fluorescence intensity Drinking water Limit of quantification(LOQ) Matrix effects

Structural and magnetic properties of micropolycrystalline cobalt thin films fabricated by direct current magnetron sputtering

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 384-394页

作者： Kerui Song Zhou Li Mei Fang Zhu Xiao qian lei School of Materials Science and Engineering Central South UniversityChangsha 410083China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Hunan Key Laboratory of Super-Microstructure and Ultrafast Process School of Physics and electronicsCentral South UniversityChangsha 410083China Key Laboratory of Non-Ferrous Metal Materials Science and Engineering Ministry of EducationChangsha 410083China

Pure cobalt(Co)thin films were fabricated by direct current magnetron sputtering,and the effects of sputtering power and pres-sure on the microstructure and electromagnetic properties of the films were investigated.As the sputtering power increases from 15 to 60 W,the Co thin films transition from an amorphous to a polycrystalline state,accompanied by an increase in the intercrystal pore width.Simultaneously,the resistivity decreases from 276 to 99μΩ·cm,coercivity increases from 162 to 293 Oe,and in-plane magnetic aniso-tropy disappears.As the sputtering pressure decreases from 1.6 to 0.2 Pa,grain size significantly increases,resistivity significantly de-creases,and the coercivity significantly increases(from 67 to 280 Oe),which can be attributed to the increase in defect width.Corres-pondingly,a quantitative model for the coercivity of Co thin films was formulated.The polycrystalline films sputtered under pressures of 0.2 and 0.4 Pa exhibit significant in-plane magnetic anisotropy,which is primarily attributable to increased microstress.

关键词： cobalt thin film magnetron sputtering microstructure electromagnetic properties

Combined effect of WS2 and Ti3C2Tx MXene favors oil-based ultra-low friction on rough steel-steel interface at elevated temperatures

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Science China Technological Sciences 2024年第7期67卷 1991-2002页

作者： LIU YangQin CHEN lei WANG Yang qian LinMao Tribology Research Institute State Key Laboratory of Rail Transit Vehicle System School of Mechanical EngineeringSouthwest Jiaotong University Key Laboratory of Advanced Technologies of Materials (Ministry of Education) Research Institute of Frontier ScienceSouthwest Jiaotong University

The lubrication performance of liquids is severely restricted and is degraded in high-temperature environments. Stable and reliable lubrication in high temperature environments has been a long-standing goal in various industrial fields. In this study,WS2and Ti3C2TxMXene nanoflakes were used as oil-based lubricant additives to generate ultra-low friction and even superlubricity（friction coefficient of ～0.007） at elevated temperatures（400°C）, which has hitherto not been achieved by both individual pristine materials, WS2and Ti3C2TxMXene. Viscosity and thermogravimetric characterization revealed improvements in the high-temperature rheological properties and thermal stability of the lubricating base oil, indicating improved loadbearing and continuous lubrication capabilities at elevated temperatures. X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy demonstrated that the formation of an iron/titanium/tungsten-rich oxide lubricious thin film at the sliding interface reduced the interfacial shear stress, which was responsible for the observed friction and wear reductions at high contact pressures（> 1.1 GPa）. Although the titanium/tungsten oxide film was gradually removed after prolonged sliding, a sufficiently thick iron oxide film maintained a low friction coefficient for at least 2 h. The improved surface quality facilitates the achievement of ultra-low friction and reduced wear. The proposed lubrication methodology has a broad utilization potential as a wear-reduction strategy across various industrial fields at elevated temperatures.

关键词： ultra-low friction high-temperature wear reduction lubricating additive tungsten disulfide MXene

A semi-analytical model for coupled flow in stress-sensitive multi-scale shale reservoirs with fractal characteristics

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Petroleum Science 2024年第1期21卷 327-342页

作者： qian Zhang Wen-Dong Wang Yu-Liang Su Wei Chen Zheng-Dong lei lei Li Yong-Mao Hao Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Shale Oil Development Branch Changqing Oilfield CompanyPetroChinaQingyang745708GansuChina PetroChina Research Institute of Petroleum Exploration&Development Beijing100083China

A large number of nanopores and complex fracture structures in shale reservoirs results in multi-scale flow of oil. With the development of shale oil reservoirs, the permeability of multi-scale media undergoes changes due to stress sensitivity, which plays a crucial role in controlling pressure propagation and oil flow. This paper proposes a multi-scale coupled flow mathematical model of matrix nanopores, induced fractures, and hydraulic fractures. In this model, the micro-scale effects of shale oil flow in fractal nanopores, fractal induced fracture network, and stress sensitivity of multi-scale media are considered. We solved the model iteratively using Pedrosa transform, semi-analytic Segmented Bessel function, Laplace transform. The results of this model exhibit good agreement with the numerical solution and field production data, confirming the high accuracy of the model. As well, the influence of stress sensitivity on permeability, pressure and production is analyzed. It is shown that the permeability and production decrease significantly when induced fractures are weakly supported. Closed induced fractures can inhibit interporosity flow in the stimulated reservoir volume (SRV). It has been shown in sensitivity analysis that hydraulic fractures are beneficial to early production, and induced fractures in SRV are beneficial to middle production. The model can characterize multi-scale flow characteristics of shale oil, providing theoretical guidance for rapid productivity evaluation.

关键词： Multi-scale coupled flow Stress sensitivity Shale oil Micro-scale effect Fractal theory

The joint knowledge reasoning model based on knowledge representation learning for aviation assembly domain

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Science China(Technological Sciences) 2024年第1期67卷 143-156页

作者： LIU PeiFeng qian Lu LU Hu XUE lei ZHAO XingWei TAO Bo State Key Laboratory of Digital Manufacturing Equipment and Technology Department of MechanicalHuazhong University of Science and TechnologyWuhan 430074China School of Transportation and Logistics Engineering Wuhan University of Technology(WHUT)Wuhan 430063China Shanghai Aircraft Manufacturing Co. Ltd.Shanghai 201324China

Knowledge graph technology is widely applied in the domain of general knowledge reasoning with an excellent performance.For fine-grained professional fields,professional knowledge graphs can provide more accurate information in practical industrial scenarios.Based on an aviation assembly domain-specific knowledge graph,the article constructs a joint knowledge reasoning model,which combines a named entity recognition model and a subgraph embedding learning model.When performing knowledge reasoning tasks,the two models vectorize entities,relationships and entity attributes in the same space,so as to share parameters and optimize learning efficiency.The knowledge reasoning model,which provides intelligent question answering services,is able to reduce the assembly error rate and improve the assembly efficiency.The system can accurately solve general knowledge reasoning problems in the assembly process in actual industrial scenarios of general assembly and component assembly under interference-free conditions.Finally,this paper compares the proposed knowledge reasoning model based on knowledge representation learning and the question-answering system based on large-scale pre-trained models.In the application scenario of system functional testing in general assembly,the joint model attains an accuracy rate of 95%,outperforming GPT with 78%accuracy and enhanced representation through knowledge integration with 71%accuracy.

关键词： intelligent manufacturing knowledge graph aviation assembly knowledge representation knowledge-based question an-swering

Detour for the inexperienced? Migration count data suggest mostly juvenile Greater Spotted Eagles appear in coastal peninsulas in China

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Avian Research 2024年第2期15卷 249-254页

作者： Xu Shi Xiaoping Wang qian Wei Qiwei Lin lei Zhu School of the Environment The University of QueenslandSt LuciaQLD4072AustraliaAustralia Centre for Ecology and Conservation and Environment and Sustainability InstituteUniversity of ExeterPenrynCornwallTR109FEUK Guangxi Biodiversity Research and Conservation Association Nanning530022China Snake Island Laotieshan National Nature Reserve Dalian116041China Chongqing Birdwatching Society Chongqing400054China Huqiu Rd Gusu DistrictSuzhou215008China Raptor Research Group of Chengdu Chengdu610000China Guangxi Academy of Marine Science Nanning530007China

Soaring bird migration often relies on suitable terrain and airflow;therefore,route selection is vital for successful migration.While age and experience have been identified as key factor influencing migration route selection among soaring raptors in the African-Eurasian Flyway,how they shape the migration route of soaring raptors in East Asia is still largely unknown.In this study,we investigated potential variations in the routes and timing in autumn migration of juvenile and older soaring birds,using count data of Greater Spotted Eagles(Clanga clanga)from two coastal sites and two inland sites in China.From 2020 to 2023,we recorded a total of 340 individuals,with the highest site averaging over 90 individuals per autumn,making it one of the world’s top single-season counts and thus a globally important site for this species.We found that 82% and 61% records from coastal sites were juveniles,significantly higher than inland sites(15% and 24%).Juveniles at all four sites exhibited markedly earlier median passage time than non-juveniles,with brief overlapping in their main migration periods.Both coastal sites are located on the tip of peninsulas stretching southwest,requiring long overwater flights if crossing the Bohai Bay or Beibu Gulf,which would be energetically demanding and increase mortality risk.Experienced individuals may have learned to avoid such terrain and subsequent detour,while juveniles are more prone to enter these peninsulas due to lack of experience and opportunities for social learning,or following other raptor species that are more capable of powered flight.Our findings highlight the importance of age and experience in migration route selection of large soaring birds.

关键词： Clanga clanga East Asia Greater Spotted Eagle Juvenile Migration route Social learning