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Radially loading rotary extrusion for manufacturing large-size conical cylinders with inner transverse high ribs

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Chinese Journal of Aeronautics 2023年第5期36卷 582-594页

作者： Zhe CHEN Zhimin ZHANG jie ZHENG yong XUE School of Material Science and Engineering North University of ChinaTaiyuan 030051China

The Large-size Conical Cylinders with Inner Transverse High Ribs(LCCWITHR) can reduce the weight of the parts while maintaining high rigidity and strength. Radially Loading Rotary Extrusion(RLRE) forming technology can achieve integral forming of LCCWITHR through the synergy of radial and rotary movements of dies. The flow law of the material during the forming process is the key to forming large-size inner ribs. At present, there is no unified understanding of the metal flow law of RLRE forming technology. An analytical expression was derived to predict the Radial Direction(RD) deformation loads. The FE simulation and process experiment were carried out to investigate the effects of the inclination angle, thickness factor and transition arc radius of the split top dies on the spacing of the metal diversion plane, the metal flow velocity of the rib area and the final radius of the inner rib. The influence of the split top dies loading distance and the bottom die rotation angle of each pass on the inner radius of the inner rib was verified. And the optimal combination of dies shape parameters and loading paths which can make the metal flow orderly was obtained: the inclination angle is 140°, the thickness factor is 3.64, the transition arc radius is 16 mm;the top dies loading distance is 15 mm, the bottom die rotation angle is 45°.The FE simulation results have been found to be in close agreement with physics *** research results reveal the metal flow law of rib growth in the RLRE of LCCWITHR, which lays a theoretical foundation for subsequent thorough research and process optimization.

关键词： Extrusion molding Rotary extrusion Radially loading Inner transverse rib Metal flow law Conical cylinder

Crystallization and heat transfer of CaO-SiO2-based slag for high-Mn-high-Al steel

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Journal of Iron and Steel Research International 2020年第7期27卷 788-795页

作者： jie Yang Deng-fu Chen Miao-yong Zhu College of Material Science and Engineering Chongqing UniversityChongqing400044China School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina

The crystallization and heat transfer of CaO-SiO2-based slag for high-Mn-high-Al steel have been investigated by coupling composition evolution with heat transfer and non-isothermal *** was found that the concentrations of Al2O3 and MnO in the slag were determined by the relative contents of Al and Mn in molten *** temperature of the slag rose with the increase in Al2O3 content first and then fell due to the coupled effects of basicity and Al2O3,and a small amount of MnO cannot change this *** viscosity of slags led to less obvious characterizations of *** crystalline phase analysis suggested that MnO accumulation suppressed the formation of fluorite *** the Al2O3 content increased,the precipitation of cuspidine was replaced by the blocky gehlenite crystals,while the number and the size of nepheline and fluorite crystals both *** to the thickness and the crystallization structure of slags,the heat flux in the slag film first decreased and then increased with higher Al2O3 ***,a new type of CaO-SiO2-based mold slag with high basicity was applied in plant trial,and the change in composition and properties of mold slag was studied.

关键词： High-Mn-high-Al steel Mold slag Al2O3 accumulation Crystallization Heat transfer

Atomic mobilities and diffusivities in Al alloys

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Science China(Technological Sciences) 2012年第2期55卷 306-328页

作者： DU yong ZHANG LiJun CUI SenLin ZHAO DongDong LIU DanDan ZHANG WeiBin sun WeiHua jie WanQi State Key Laboratory for Powder Metallurgy Central South UniversityChangsha 410083China Interdisciplinary Centre for Advanced Materials Simulation Ruhr-Universitat BochumBochumGermany State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China

Knowledge of diffusivity is a prerequisite for understanding many scientific and technological disciplines. In this paper, firstly major experimental methods, which are employed to provide various diffusivity data, are briefly described. Secondly, the fun-damentals of various computational methods, including first-principles method, embedded atomic method/molecular dynamic simulation, semi-empirical approaches, and phenomenological DICTRA technique, are demonstrated. Diffusion models re- cently developed for order/disorder transitions and stoichiometric compounds are also briefly depicted. Thirdly, a newly estab- lished diffusivity database for liquid, fcc_A1, Lie, bcc_A2, bcc_B2, and interrnetallic phases in the multicomponent A1 alloys is presented via a few case studies in binary, ternary and quaternary systems. And the integration of various computational techniques and experimental methods is highlighted. The reliability of this diffusivity database is validated by comparing the calculated and measured concentration profiles, diffusion paths, and Kirkendall shifts in various binary, ternary and quaternary diffusion couples. Next, the established diffusivity databases along with thermodynamic and other thermo-physical properties are utilized to simulate the microstructural evolution for Al alloys during solidification, interdiffusion and precipitation. A spe- cial discussion is presented on the phase-field simulation of interdiffusion microstructures in a series of Ni-Al diffusion couples composed of γ, γ＇, and β phases under the effects of both coherent strain and external compressive force. Future orientations in the establishment of next generation of diffusivity database are finally addressed.

关键词： AI alloys kinetics atomic mobilities diffusion DICTRA first-principles calculation phase-field simulation

Thermodynamic analysis and kinetic optimization of high-energy batteries based on multi-electron reactions

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National Science Review 2020年第8期7卷 1367-1386页

作者： yong-Xin Huang Feng Wu Ren-jie Chen Beijing Key Laboratory of Environmental Science and Engineering School of Materials Science and Engineering Beijing Institute of Technology Advanced Technology Research Institute (Jinan) Beijing Institute of Technology Collaborative Innovation Center of Electric Vehicles in Beijing

Multi-electron reaction can be regarded as an effective way of building high-energy systems(>500 W h kg-1). However, some confusions hinder the development of multi-electron mechanisms, such as clear concept, complex reaction, material design and electrolyte optimization and full-cell ***, this review discusses the basic theories and application bottlenecks of multi-electron mechanisms from the view of thermodynamic and dynamic principles. In future, high-energy batteries,metal anodes and multi-electron cathodes are promising electrode materials with high theoretical capacity and high output voltage. While the primary issue for the multi-electron transfer process is sluggish kinetics,which may be caused by multiple ionic migration, large ionic radius, high reaction energy barrier, low electron conductivity, poor structural stability, etc., it is urgent that feasible and versatile modification methods are summarized and new inspiration proposed in order to break through kinetic ***, the remaining challenges and future research directions are revealed in detail, involving the search for high-energy systems, compatibility of full cells, cost control, etc.

关键词： multi-electron reactions thermodynamic kinetics high-energy density metal anodes

GGC:Gray-Granger Causality Method for Sensor Correlation Network Structure Mining on High-Speed Train

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Tsinghua Science and Technology 2022年第1期27卷 207-222页

作者： jie Man Honghui Dong Limin Jia yong Qin the State Key Laboratory of Rail Traffic Control and Safety and Beijing Research Center of Urban Traffic Information Sensing and Service TechnologiesBeijing Jiaotong UniversityBeijing 100044China

Vehicle information on high-speed trains can not only determine whether the various parts of the train are working normally,but also predict the train’s future operating *** to obtain valuable information from massive vehicle data is a difficult ***,we divide the vehicle data of a high-speed train into 13 subsystem datasets,according to the functions of the collection ***,according to the gray theory and the Granger causality test,we propose the Gray-Granger Causality(GGC)model,which can construct a vehicle information network on the basis of the correlation between the collection *** using the complex network theory to mine vehicle information and its subsystem networks,we find that the vehicle information network and its subsystem networks have the characteristics of a scale-free *** addition,the vehicle information network is weak against attacks,but the subsystem network is closely connected and strong against attacks.

关键词： vehicle information network structure mining gray theory Granger causality theory complex network theory high-speed train

A survey of prototype and experiment for UAV communications

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Science China(Information Sciences) 2021年第4期64卷 5-25页

作者： Qingheng SONG yong ZENG jie XU Shi JIN College of Electrical and Information Engineeing Huaihua University Key Laboratory of Intelligent Control Technology for Wuling-Mountain Ecological Agriculture in Hunan Province National Mobile Communications Research Laboratory Southeast University Future Network of Intelligence Institute (FNii) and School of Science and Engineering The Chinese University of Hong Kong (Shenzhen)

Unmanned aerial vehicle(UAV) communications have attracted significant attention from both academia and industry. To facilitate the large-scale usage of UAVs for various applications in practice,we provide a comprehensive survey on the prototype and experiment for UAV communications. To this end, we first provide an overview on the general architecture of the prototype and experiment for UAV communications, and then present experimental verification for air-to-ground channel models and UAV energy consumption models. Next, we discuss measurement experiments on two promising paradigms of UAV communications, namely cellular-connected UAVs and UAV-enabled aerial communication platforms. For the former, we focus on the feasibility study and address the interference mitigation issue. For UAV-enabled aerial communication platforms, we present three scenarios, namely UAV-enabled aerial base stations, UAVenabled aerial relays and UAV-enabled aerial data collection/dissemination. Finally, we point out some promising future directions for prototype and experimental measurements of UAV communications.

关键词： UAV communications prototype development channel model energy efficiency UAV-enabled communications platforms cellular-connected UAVs

Intelligent optimization of seam-line finding for orthophoto mosaicking with LiDAR point clouds

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Journal of Zhejiang University-Science C(Computers and Electronics) 2011年第5期12卷 417-429页

作者： Hong-chao MA jie sun School of Remote Sensing Wuhan University Wuhan 430079 China State Key Lab for Surveying Mapping and Remote Sensing Wuhan University Wuhan 430079 China

A detailed study was carried out to find optimal seam-lines for mosaicking of images acquired by an airborne light detection and ranging (LiDAR) *** ground objects labeled as obstacles can be identified by delineating black holes from filtered point clouds obtained by filtering the raw laser scanning *** innovative A algorithm is proposed that can automatically make the seam-lines keep away from these obstacles in the registered *** method can intelligently optimize the selection of seam-lines and improve the quality of orthophotos.A simulated grid image was first used to analyze the effect of different heuristic functions on path *** subsets of LiDAR data from Xi'an,Dunhuang,and Changyang in Northwest China were obtained.A quantitative method including pixel intensity,hue,and texture was *** our proposed method,9.4%,8.7%,and 9.8% improvements were achieved in Dunhuang,Xi'an,and Changyang,respectively.

关键词： Light detection and ranging (EiDAR) Filter A* algorithm Mosaicking Seam-line

Machine learning for accelerating the discovery of high-performance donor/acceptor pairs in non-fullerene organic solar cells

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npj Computational Materials 2020年第1期6卷 645-652页

作者： Yao Wu jie Guo Rui sun jie Min The Institute for Advanced Studies Wuhan UniversityWuhan 430072China Beijing National Laboratory for Molecular Sciences Beijing 100190China

Integrating artificial intelligence(AI)and computer science together with current approaches in material synthesis and optimization will act as an effective approach for speeding up the discovery of high-performance photoactive materials in organic solar cells(OSCs).Yet,like model selection in statistics,the choice of appropriate machine learning(ML)algorithms plays a vital role in the process of new material discovery in *** this study,we constructed five common algorithms,and introduced 565 donor/acceptor(D/A)combinations as training data sets to evaluate the practicalities of these ML algorithms and their application potential when guiding material design and D/A pairs screening.

关键词： donor acceptor performance

Boundedness of parammetric Marcinkiewicz integrals on weighted Hardy spaces

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Applied Mathematics(A Journal of Chinese Universities) 2015年第3期30卷 253-262页

作者： SHI Xian-liang sun jie College of Mathematics and Computer Science Key Laboratory of High Performance Computing and Stochastic Information Processing (HPCSIP) (Ministry of Education of China) Hunan Normal University

In this paper, several new results on the boundedness of parammetric Marcinkiewicz integrals on the weighted Hardy spaces and the weak weighted Hardy spaces are established.

关键词： parammetric Marcinkiewicz integral weight function weighted Hardy space weak weighted Hardy space