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Orientation-Dependent Mechanical Responses and Plastic Deformation Mechanisms of FeMnCoCrNi High-entropy Alloy:A Molecular Dynamics Study

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Acta Metallurgica Sinica(English Letters) 2021年第11期34卷 1511-1526页

作者： Hai-Feng Zhang Hai-Le Yan Feng Fang nan jia Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang 110819China State Key Lab Rolling&Automat Northeastern UniversityShenyang 110819China

Mechanical properties of high-entropy alloys(HEAs)with the face-centered cubic(fcc)structure strongly depend on their initial grain ***,the orientation-dependent mechanical responses and the underlying plastic fl ow mechanisms of such alloys are not yet well ***,deformation of the equiatomic FeMnCoCrNi HEA with various initial orientations under uniaxial tensile testing has been studied by using atomistic simulations,showing the results consistent with the recent experiments on fcc *** quantitative analysis of the activated deformation modes shows that the initiation of stacking faults is the main plastic deformation mechanism for the crystals initially oriented with[001],[111],and[112],and the total dislocation densities in these crystals are higher than that with the[110]and[123]*** faults,twinning,and hcp-martensitic transformation jointly promote the plastic deformation of the[110]orientation,and twinning in this crystal is more significant than that with other *** in the crystal oriented with[123]is dominated by the hcp-martensite *** of the mechanical behaviors in the FeMnCoCrNi alloy and the conventional materials,*** and Fe50Ni50,has shown that dislocation slip tends to be activated more readily in the *** is attributed to the larger lattice distortion in the HEA than the low-entropy materials,leading to the lower critical stress for dislocation nucleation and elastic–plastic transition in the *** addition,the FeMnCoCrNi HEA with the larger lattice distortion leads to an enhanced capacity of storing ***,for the[001]-oriented HEA in which dislocation slip and stacking fault are the dominant deformation mechanisms,the limited deformation modes activated are insu fficient to improve the work hardening ability of the material.

关键词： High-entropy alloy Molecular dynamics study Mechanical response Plastic deformation mechanism

Anti-jamming channel access in 5G ultra-dense networks: a game-theoretic learning approach

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Digital Communications and Networks 2023年第2期9卷 523-533页

作者： Yunpeng Zhang Luliang jia nan Qi Yifan Xu Meng Wang College of Communications Engineering Army Engineering University of PLANanjing210007China School of Space Information Space Engineering UniversityBeijing101416China College of Electronic and Information Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016China

This paper investigates the Quality of Experience(QoE)oriented channel access anti-jamming problem in 5th Generation Mobile Communication(5G)ultra-dense ***,considering that the 5G base station adopts beamforming technology,an anti-jamming model under Space Division Multiple Access(SDMA)conditions is ***,the confrontational relationship between users and the jammer is formulated as a Stackelberg ***,to achieve global optimization,we design a local cooperation mechanism for users and formulate the cooperation and competition among users as a local altruistic *** proving that the local altruistic game is an Exact Potential Game(EPG),we further prove the existence of pure strategy Nash Equilibrium(NE)among users and Stackelberg Equilibrium(SE)between users and ***,to obtain the equilibrium solutions of the proposed games,we propose an anti-jamming channel selection algorithm and improve its convergence speed through heterogeneous learning *** simulation results validate the convergence and effectiveness of the proposed *** with the throughput optimization scheme,our proposed scheme obtain a greater network satisfaction ***,we also analyze user fairness changes during the algorithm convergence process and get some interesting conclusions.

关键词： Anti-jamming 5G Ultra-dense networks Stackelberg game Exact potential game Channel selection algorithm

Synergy effect of multi-strengthening mechanisms in FeMnCoCrN HEA at cryogenic temperature

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Journal of Materials Science & Technology 2021年第27期86卷 158-170页

作者： Zhufeng He nan jia Hongwei Wang Haile Yan Yongfeng Shen Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang 110819China State Key Lab Rolling&Automat Northeastern UniversityShenyang 110819China

High-entropy alloys(HEAs)have attracted great research interest owing to their good combination of high strength and ductility at both room and cryogenic ***,expensive raw materials are always added to overcome the strength-ductility trade-off at low temperatures,leading to an increased production cost for the cryogenically used *** this work,a series of nitrogen-doped Fe Mn Co Cr HEAs have been processed by homogenization annealing,cold rolling and recrystallization annealing followed by water *** microstructural evolution and mechanical properties of the alloys are studied *** Fe_(49)Mn_(30)Co_(10)Cr_(10)N1alloy shows excellent mechanical properties at both 293 K and 77 ***,the yield and ultimate tensile strength of 1078 and 1630 MPa are achieved at the cryogenic temperature,respectively,while a satisfactory uniform elongation of 33.5%is *** ultrahigh yield strength results from the microstructure refinement caused by the activation of athermal martensitic transformation and mechanical twinning that occur in the elastic regime together with the increased lattice friction due to the cryogenic *** the plastic regime,the dynamic Hall-Petch effect caused by twinning,martensitic transformation,and reverse transformation together with the high barrier to dislocation motion jointly contribute to the ultrahigh tensile ***,the transformation induced plasticity(TRIP)and the twinning induced plasticity(TWIP)effects jointly contribute to the *** design strategy for attaining superior mechanical properties at low temperatures,*** adjusting stacking fault energy in the interstitial metastable HEAs,guides the development of high-performance and low-cost alloys for cryogenic applications.

关键词： High-entropy alloy Cryogenic deformation Nitrogen doping Phase transformation Twinning

Abnormal chemical composition fluctuations in multi-principal-element alloys induced by simple cyclic deformation

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Journal of Materials Science & Technology 2022年第18期113卷 287-295页

作者： Mengyuan He nan jia Xiaochun Liu Yongfeng Shen Liang Zuo Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Institute of Metals College of Materials Science and EngineeringChangsha University Of Science and TechnologyChangsha 410114China

High entropy alloys exhibit excellent combination of mechanical properties because of the unique com-position fluctuations,termed as‘concentration wave’.The concentration wave was closely related to mul-tiple aspects,including the fluctuation of local strain energy,local atomic environment,electronegativity,*** we report for the first time that the amplitude of the concentration wave can be mechani-cally tailored under cyclic deformation in a well-known Cantor ***-scale energy-dispersive X-ray spectroscopy(EDS)mapping reveals that cyclic deformation may dynamically induce the clustering of solute atoms with a size of 1-3 nm,thus resulting in a higher concentration wave *** con-centration wave promotes strong interactions between dislocations and local solute *** from the typical Taylor strengthening contribution due to the presence of isolated dislocations,the strength enhancement from the mechanically induced composition fluctuations was quantified to be as high as∼70 MPa,about one-third of the yield strength of the alloy without *** opens up a novel strategy of designing high strength alloys by tailoring solute configurations.

关键词： Cantor alloy Cyclic deformation Concentration wave EDS maps

Towards privacy-preserving and efficient word vector learning for lightweight IoT devices

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Digital Communications and Networks 2024年第4期10卷 895-903页

作者： nan jia Shaojing Fu Guangquan Xu Kai Huang Ming Xu National University of Defense Technology ChangshaChina Big Data School Qingdao Huanghai UniversityQingdaoChina Tianjin Key Laboratory of Advanced Networking College of Intelligence and ComputingTianjin UniversityTianjinChina College of Joint Operations National Defense UniversityShijiazhuangChina

Nowadays,Internet of Things(IoT)is widely deployed and brings great opportunities to change people's daily *** realize more effective human-computer interaction in the IoT applications,the Question Answering(QA)systems implanted in the IoT services are supposed to improve the ability to understand natural ***,the distributed representation of words,which contains more semantic or syntactic information,has been playing a more and more important role in the QA ***,learning high-quality distributed word vectors requires lots of storage and computing resources,hence it cannot be deployed on the resource-constrained IoT *** is a good choice to outsource the data and computation to the cloud ***,it could cause privacy risks to directly upload private data to the untrusted ***,realizing the word vector learning process over untrusted cloud servers without privacy leakage is an urgent and challenging *** this paper,we present a novel efficient word vector learning scheme over encrypted *** first design a series of arithmetic computation *** we use two non-colluding cloud servers to implement high-quality word vectors learning over encrypted *** proposed scheme allows us to perform training word vectors on the remote cloud servers while protecting *** analysis and experiments over real data sets demonstrate that our scheme is more secure and efficient than existing privacy-preserving word vector learning schemes.

关键词： Privacy-preserving Word vector learning Secret sharing Internet of things

Reverse Transformation in[110]-Oriented Face-Centered-Cubic Single Crystals Studied by Atomic Simulations

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Acta Metallurgica Sinica(English Letters) 2022年第10期35卷 1631-1640页

作者： Hai-Feng Zhang Hai-Le Yan Feng Fang nan jia Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang110819China State Key Lab Rolling&Automat Northeastern UniversityShenyang110819China

Bidirectional transformations,which are achieved by triggering both dynamic forward transformation from the face-centered-cubic(fcc)austenite to the hexagonal-close-packed(hcp)martensite and the reverse transformation from martensite to austenite during cold deformation,have been previously reported in FeMnCoCr-based high-entropy alloys(HEAs).This leads to the permanent refinement of microstructure and hence enhances the work-hardening capacity of *** order to reveal the microscopic mechanism of the reverse transformation in HEAs under deformation,the effect of the sample aspect ratio,i.e.,Z/X,on the evolution of deformation systems in the equi-atomic FeMnCoCrNi alloy with[110]orientation during uniaxial tensile loading along the Z direction is investigated by atomic simulations in this *** the aspect ratio is 0.5,the reverse transformation is more significant compared with other models,while a good plasticity can still be *** then compare the micromechanical behavior of three fcc single crystals,i.e.,FeMnCoCrNi,FeCuCoCrNi,and pure *** results show that the stacking fault energy plays a major role in the activation of different deformation mechanisms;however,the lattice distortion in the HEA does not significantly affect the activation of deformation ***,for all materials dislocation slip leads to the softening,while strain hardening is attributed to the initiation of multiple deformation *** Shockley partials slip leads to bidirectional phase transition,twinning and detwinning in the three ***,the reverse transformation can occur in all metallic materials where the fcc to hcp phase transformation is the dominant deformation *** findings contribute to an in-depth understanding of the deformation mechanism in fcc-structured materials under severe plastic deformation and provide theoretical guidance for the design of alloys with superior strength–plasticity combinations.

关键词： Face-centered-cubic materials Atomic simulation Plastic deformation Reverse transformation

A Simulation of the Response of a Sounding Temperature Sensor Based on the Combination of a Genetic Algorithm and Computational Fluid Dynamics

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Fluid Dynamics & Materials Processing 2020年第6期16卷 97-111页

作者： Juanjuan Wang Yajuan jia jiangping nan Xi’an Traffic Engineering Institute Xi’an710300China

The present study aims at improving the accuracy of weather forecast by providing useful information on the behavior and response of a sounding temperature sensor.A hybrid approach relying on Computational Fluid Dynamics and a genetic algorithm(GA)is used to simulate the system represented by the bead thermistor and the surrounding *** particular,the influence of different lead angles,sensor lead length,and lead number is *** results have shown that when the length of the lead wire of the bead thermistor is increased,the radiation temperature rise is reduced;when the number of lead wire is four and the angle between the lead wires is 180°,the solar radiation angle has a scarce influence on the radiation temperature rise of the sounding temperature sensor.

关键词： Sounding temperature sensor genetic algorithm radiation temperature rise computational fluid dynamics bead thermistor

Role of mountains and rivers in the formation of logistics enterprises'spatial pattern in the central urban areas of Chongqing

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Journal of Mountain Science 2022年第7期19卷 2060-2074页

作者： LIU Si-jing ZHU Cheng-jia HE nan-nan LI Guo-qi School of Transportation and Logistics Southwest Jiaotong UniversityChengdu611756China National Engineering Laboratory of Integrated Transportation Big Data Application Technology Chengdu611756China National United Engineering Laboratory of Integrated and Intelligent Transportation Chengdu611756China

The complex landforms of a Shan-shui City(Shan-shui refers to mountains and rivers)significantly impact the selection of locations for logistics *** paper takes Chongqing,one of the most typical Shan-shui Cities in China,as the research object,and adopts spatial analysis methods and a mediating effect model,to explore the role of mountains and rivers in the formation of logistics enterprises’spatial pattern on the street *** study results reveal that 90% of the logistics enterprises in the central urban areas of Chongqing are located in the low-altitude area below 353m above sea level,and distributed in a north-south direction along the mountains,as a result of blockage by mountain ranges,such as those of Zhongliang Mountain and Tongluo *** than 70% of the logistics enterprises are located less than 5 km from either the Yangtze River or jialing River,spreading along the *** addition,more than half of the logistics enterprises in commercial and financial,and residential land are located within the urban core area,while 80.83% of the logistics enterprises located in warehousing land and industrial land are concentrated in the urban expansion *** areas with high land prices,the negative effect of altitude on logistics enterprise agglomeration is weakened,while the promotion effect of river proximity on logistics enterprise agglomeration is *** the urban core area with the advantage of low altitude and proximity to the jialing and Yangtze Rivers,the role of mountains and rivers on logistics enterprises is not apparent;in contrast,in the urban expansion area with more complex landforms,land price can be an effective means for the government to macro-manage the spatial pattern of logistics enterprises in a Shan-shui City.

关键词： Logistics enterprise Spatial pattern Influencing factors Driving mechanism Chongqing

Dr. jian Zhou： The great inventor of cervical ：ancer vaccine

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Protein & Cell 2017年第2期8卷 79-82页

作者： Kong-nan Zhao Lifang Zhang jia Qu Institute of Molecular Virology and Immunology Wenzhou Medical University Wenzhou 325035 China Centre for Clinical Research Translational Research Institute The University of Queensland School of Medicine 37 Kent Street Woolloongabba Brisbane QLD 4102 Australia Laboratory of Neurovascular Biology School of Ophthalmology and Optometry and the Eye Hospital of Wenzhou Medical University Wenzhou 325003 China The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science Ministry of Health Wenzhou 325027 China

In November 2005, scientists gathered at Times Square in New York City announced the exciting news of the successful development of the world＇s first cervical cancer vaccine. The cervical cancer vaccine, which is able to protect unexposed women against the infection with four HPV strains responsible for 70% of cervical cancers, was approved for human use by the US Federal Drug Administration （FDA） and a number of other countries.

关键词： cancer cervical inventor