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China Foundry 2024年第3期21卷 205-212页

作者： Guan-yu Jiang Meng-wu Wu Xiao-guang Yang Hui wang Yu-yuan Zhu Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China Hubei Longzhong Laboratory Xiangyang 441000HubeiChina Wescast Industries(China)Co. Ltd.Wuhan 430100China

Three types of steels were designed on the basis of GX40CrNiSi25-12 austenitic heat resistant steel by adding different Mn contents(2wt.%,6wt.%,and 12wt.%).Thermodynamic calculation,microstructure characterization and mechanical property tests were conducted to investigate the effect of Mn addition on the microstructure and mechanical properties of the austenitic heat resistant *** show that the matrix structure in all the three types of steels at room temperature is completely *** NbC and M_(23)C_(6)precipitate at grain boundaries of austenite *** the increase of Mn content,the number of carbides increases and their distribution becomes more *** the Mn content increases from 1.99%to 12.06%,the ultimate tensile strength,yield strength and elongation increase by 14.6%,8.0%and 46.3%,*** improvement of the mechanical properties of austenitic steels can be explained by utilizing classic theories of alloy strengthening,including solid solution strengthening,precipitation strengthening,and grain *** increase in alloy strength can be attributed to solid solution strengthening and precipitation strengthening caused by the addition of *** improvement of the plasticity of austenitic steels can be explained from two aspects:grain refinement and homogenization of precipitated phases.

关键词： austenitic heat resistant steel manganese microstructure mechanical properties

Optimization of mixing speed and time to disperse the composite conductive agent composed of carbon black and graphene in lithium-ion battery slurry

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Particuology 2024年第9期92卷 1-12页

作者： Zhilong wang Jialong Tu Xinhao Yu Feixiang Li Zhenzhen Zhao Yahui Cui Tong Zhao Faculty of Mechanical and Precision Instrument Engineering Xi'an University of TechnologyXi'an710048China

This paper proposed an optimal approach to disperse the composite conductive agent which is composed of carbon black(CB)and graphene(Gr)within lithium-ion battery(LIB)slurry with different mixing speeds and mixing *** internal structures of LIB slurry are characterized by Electrochemical Impedance Spectroscopy,Scanning Electron Microscopy,and Raman ***,a composite conductive solution is prepared by mixing the composite conductive agent with NMP solvent under the conditions of five different mixing speeds n_(1)(n_(1)=1000,1100,1200,1300,1400 rpm)in the case of mixing time t_(1)=10 ***,LIB slurry is prepared by blending the composite conductive solution,LiCoO_(2)and PVDF-NMP solution under the conditions of five different mixing speeds n_(2)(n_(2)=1000±280,1100±280,1200±280,1300±280,1400±280 rpm)in the case of mixing time t_(2)=6 *** analyzing the internal structure of different LIB slurries,it shows that in the case of n_(1)=n_(2)=1200 rpm,a conductive network structure is well formed within LIB ***,in order to determine the optimal time to prepare the composite conductive solution for LIB slurry,nine different t_(1)(t_(1)=0,10,20,30,40,50,60,70,80 min)are *** analyzing the internal structure of different LIB slurries,a well-formed conductive network structure and a uniformly distributed composite conductive agent are deduced in LIB slurry when t_(1)=50 ***,it can be concluded that the composite conductive agent composed of CB and Gr is able to be uniformly dispersed in LIB slurry by establishing a well-formed conductive network structure under the optimal mixing speed n_(1)=n_(2)=1200 rpm and the optimal mixing time t_(1)=50 min,t_(2)=6 *** kind of the internal structure has the potential to be used to further analyze the dispersion characterizations of LIB slurry under different composite conductive agent and CB/Gr ratios with the aim of improving the final performance of LIB.

关键词： Lithium-ion battery slurry Composite conductive agent Carbon black Graphene

Combining reinforcement learning with mathematical programming:An approach for optimal design of heat exchanger networks

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Chinese Journal of Chemical Engineering 2024年第5期69卷 63-71页

作者： Hui Tan Xiaodong Hong Zuwei Liao Jingyuan Sun Yao Yang Jingdai wang Yongrong Yang State Key Laboratory of Chemical Engineering College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China ZJU-Hangzhou Global Scientific and Technological Innovation Center Hangzhou 311215China

Heat integration is important for energy-saving in the process *** is linked to the persistently challenging task of optimal design of heat exchanger networks(HEN).Due to the inherent highly nonconvex nonlinear and combinatorial nature of the HEN problem,it is not easy to find solutions of high quality for large-scale *** reinforcement learning(RL)method,which learns strategies through ongoing exploration and exploitation,reveals advantages in such ***,due to the complexity of the HEN design problem,the RL method for HEN should be dedicated and designed.A hybrid strategy combining RL with mathematical programming is proposed to take better advantage of both *** insightful state representation of the HEN structure as well as a customized reward function is introduced.A Q-learning algorithm is applied to update the HEN structure using theε-greedy *** results are obtained from three literature cases of different scales.

关键词： Heat exchanger network Reinforcement learning Mathematical programming Process design

Serological Investigation into the Infected Genotypes of Patients with Japanese Encephalitis in the Coastal Provinces of China

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Biomedical and Environmental Sciences 2024年第7期37卷 716-725页

作者： Weijia Zhang Jierong Zhao Qikai Yin Shenghui Liu Ruichen wang Shihong Fu Fan Li Ying He Kai Nie Guodong Liang Songtao Xu Guang Yang Huanyu wang National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases National Institute for Viral Disease Control and PreventionChinese Center for Disease Control and PreventionBeijing 102206China School of Basic Medicine and Public Health Jinan UniversityGuangzhou 510000GuangdongChina

Objective Genotypes(G)1,3,and 5 of the Japanese encephalitis virus(JEV)have been isolated in China,but the dominant genotype circulating in Chinese coastal areas remains *** searched for G5 JEV-infected cases and attempted to elucidate which JEV genotype was most closely related to human Japanese encephalitis(JE)in the coastal provinces of *** In this study,we collected serum specimens from patients with JE in three coastal provinces of China(Guangdong,Zhejiang,and Shandong)from 2018 to 2020 and conducted JEV cross-neutralization tests against G1,G3,and *** Acute serum specimens from clinically reported JE cases were obtained for laboratory confirmation from hospitals in Shandong(92 patients),Zhejiang(192 patients),and Guangdong(77 patients),China,from 2018 to *** of the 361 serum specimens were laboratory-confirmed to be infected with *** cases were confirmed to be infected with G1 JEV,32 with G3 JEV,and two with G5 *** G3 was the primary infection genotype among JE cases with a definite infection genotype,and the infection caused by G5 JEV was confirmed serologically in China.

关键词： Japanese encephalitis virus Serological investigation Plaque reduction neutralization test Cross-neutralization test Genotype

Economical Quadrupedal Multi-Gait Locomotion via Gait-Heuristic Reinforcement Learning

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Journal of Bionic Engineering 2024年第4期21卷 1720-1732页

作者： Lang Wei Jinzhou Zou Xi Yu Liangyu Liu Jianbin Liao Wei wang Tong Zhang School of Power and Mechanical Engineering Wuhan UniversityLuojiashanWuhan430072HubeiChina State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityLuojiashanWuhan430072HubeiChina

In order to strike a balance between achieving desired velocities and minimizing energy consumption,legged animals have the ability to adopt the appropriate gait pattern and seamlessly transition to another if *** ability makes them more versatile and efficient when traversing natural terrains,and more suitable for long *** the same way,it is meaningful and important for quadruped robots to master this *** achieve this goal,we propose an effective gait-heuristic reinforcement learning framework in which multiple gait locomotion and smooth gait transitions automatically emerge to reach target velocities while minimizing energy *** incorporate a novel trajectory generator with explicit gait information as a memory mechanism into the deep reinforcement learning *** allows the quadruped robot to adopt reliable and distinct gait patterns while benefiting from a warm start provided by the trajectory ***,we investigate the key factors contributing to the emergence of multiple gait *** tested our framework on a closed-chain quadruped robot and demonstrated that the robot can change its gait patterns,such as standing,walking,and trotting,to adopt the most energy-efficient gait at a given ***,we deploy our learned controller to a quadruped robot and demonstrate the energy efficiency and robustness of our method.

关键词： Legged robots Deep reinforcement learning Central pattern generator Quadrupedal gait

In-situ additive manufacturing of high strength yet ductility titanium composites with gradient layered structure using N_(2)

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International Journal of Extreme Manufacturing 2024年第3期6卷 387-409页

作者： Yunmian Xiao Changhui Song Zibin Liu Linqing Liu Hanxiang Zhou Di wang Yongqiang Yang School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou 510641People’s Republic of China

It has always been challenging work to reconcile the contradiction between the strength and plasticity of titanium *** powder bed fusion(LPBF) is a convenient method to fabricate innovative composites including those inspired by gradient layered *** this work,we used LPBF to selectively prepare Ti N/Ti gradient layered structure(GLSTi)composites by using different N_(2)–Ar ratios during the LPBF *** systematically investigated the mechanisms of in-situ synthesis Ti N,high strength and ductility of GLSTi composites using microscopic analysis,TEM characterization,and tensile testing with digital image ***,a digital correspondence was established between the N_(2) concentration and the volume fraction of LPBF in-situ synthesized Ti *** results show that the GLSTi composites exhibit superior mechanical properties compared to pure titanium fabricated by LPBF under pure ***,the tensile strength of GLSTi was more than 1.5times higher than that of LPBF-formed pure titanium,reaching up to 1100 MPa,while maintaining a high elongation at fracture of 17%.GLSTi breaks the bottleneck of high strength but low ductility exhibited by conventional nanoceramic particle-strengthened titanium matrix composites,and the hetero-deformation induced strengthening effect formed by the Ti N/Ti layered structure explained its strength-plasticity balanced *** microhardness exhibits a jagged variation of the relatively low hardness of 245 HV0.2 for the pure titanium layer and a high hardness of 408 HV0.2 for the N_(2) in-situ synthesis *** study provides a new concept for the structure-performance digital customization of 3D-printed Ti-based composites.

关键词： laser powder bed fusion layered structure composites in-situ synthesis TiN strength-plasticity synergy

Near infrared emissions from both high efficient quantum cutting (173%) and nearly-pure-color upconversion in NaY(WO_(4))_(2):Er^(3+)/Yb^(3+) with thermal management capability for silicon-based solar cells

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Light(Science & Applications) 2024年第1期13卷 113-126页

作者： Duan Gao Baojiu Chen Xuezhu Sha Yuhang Zhang Xin Chen Li wang Xizhen Zhang Jinsu Zhang Yongze Cao Yichao wang Lei Li Xiangping Li Sai Xu Hongquan Yu Lihong Cheng School of Science Dalian Maritime UniversityDalian 116026 LiaoningChina

Raising photoelectric conversion efficiency and enhancing heat management are two critical concerns for siliconbased solar *** this work,efficient Yb^(3+) infrared emissions from both quantum cutting and upconversion were demonstrated by adjusting Er^(3+) and Yb^(3+) concentrations,and thermo-manage-applicable temperature sensing based on the luminescence intensity ratio of two super-low thermal quenching levels was discovered in an Er^(3+)/Yb^(3+) codoped tungstate *** quantum cutting mechanism was clearly decrypted as a two-step energy transfer process from Er^(3+) to Yb^(3+).The two-step energy transfer efficiencies,the radiative and nonradiative transition rates of all interested 4 f levels of Er^(3+) in NaY(WO_(4))_(2) were confirmed in the framework of Föster-Dexter theory,Judd-Ofelt theory,and energy gap law,and based on these obtained efficiencies and rates the quantum cutting efficiency was furthermore determined to be as high as 173%in NaY(WO_(4))_(2):5 mol%Er^(3+)/50 mol%Yb^(3+) *** and nearly pure infrared upconversion emission of Yb3+under 1550 nm excitation was achieved in Er^(3+)/Yb^(3+)co-doped NaY(WO_(4))_(2) by adjusting Yb^(3+) doping *** Yb^(3+) induced infrared upconversion emission enhancement was attributed to the efficient energy transfer ^(4)I_(11/2)(Er^(3+))+^(2)F_(7/2)(Yb^(3+))→^(4)I_(15/2)(Er^(3+))+^(2)F_(5/2)(Yb^(3+))and large nonradiative relaxation rate of ^(4)I_(9/2).Analysis on the temperature sensing indicated that the NaY(WO_(4))_(2):Er^(3+)/Yb^(3+)serves well the solar cells as thermos-managing ***,it was confirmed that the fluorescence thermal quenching of ^(2)H_(11/2)/^(4)S_(3/2) was caused by the nonradiative relaxation of ^(4)S_(3/2).All the obtained results suggest that NaY(WO_(4))_(2):Er^(3+)/Yb^(3+) is an excellent material for silicon-based solar cells to improve photoelectric conversion efficiency and thermal management.

关键词： quantum thermal relaxation

A healable, mechanically robust and ultrastretchable ionic conductive elastomer for durably wearable sensor

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Nano Research 2024年第4期17卷 3369-3378页

作者： Guoxian Zhang Chunmei Li JiaoJun Tan Mingqi wang Yafeng Ren Feijie Ge Qiuyu Zhang Key Laboratory of Special Functional and Smart Polymer Materials of Ministry of Industry and Information Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi'an 710072China College of Bioresources Chemical and Materials Engineering National Demonstration Center for Experimental Light Chemistry Engineering EducationShaanxi University of Science&TechnologyXi’an 710021China

The ionic conductive elastomers show great promise in multifunctional wearable electronics,but they currently suffer from liquid leakage/evaporation or mechanical *** ionic conductive elastomers integrating non-volatility,mechanical robustness,superior ionic conductivity,and ultra-stretchability remains urgent and ***,we developed a healable,robust,and conductive elastomer via impregnating free ionic liquids(ILs)into the ILs-multigrafted poly(urethane-urea)(PUU)elastomer networks.A crucial strategy in the molecular design is that imidazolium cations are largely introduced by double-modification of PUU and centipede-like structures are obtained,which can lock the impregnated ILs through strong ionic *** this system,the PUU matrix contributes outstanding mechanical properties,while the hydrogen bonds and ionic interactions endow the elastomer with self-healing ability,conductivity,as well as non-volatility and *** fabricated ionic conductive elastomers show good conductivity(3.8×10^(-6) S·cm^(-1)),high mechanical properties,including tensile stress(4.64 MPa),elongation(1470%),and excellent healing ability(repairing efficiency of 90%after healing at room temperature for 12 h).Significantly,the conductive elastomers have excellent antifatigue properties,and demonstrate a highly reproducible response after 1000 uninterrupted extension-release *** work provides a promising strategy to prepare ionic conductive elastomers with excellent mechanical properties and stable sensing capacity,and further promote the development of mechanically adaptable intelligent sensors.

关键词： ionic conductive elastomers poly(urethane-urea)(PUU) ionic interactions centipede-like self-healing

Conventional and micro scale finite element modeling for metal cutting process:A review

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Chinese Journal of Aeronautics 2024年第2期37卷 199-232页

作者： Le wang Caixu YUE Xianli LIU Ming LI Yongshi XU Steven Y.LIANG Key Laboratory of Advanced Manufacturing and Intelligent Technology Ministry of EducationHarbin University of Science and TechnologyHarbin 150080China George W.Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlanta 30332USA

The metal cutting process is accompanied by complex stress field,strain field,temperature *** comprehensive effects of process parameters on chip morphology,cutting force,tool wear and residual stress are complex and *** element method(FEM)is considered as an effective method to predict process variables and reveal microscopic physical phenomena in the cutting ***,the finite element(FE)simulation is used to research the conventional and micro scale cutting process,and the differences in the establishment of process variable FE simulation models are distinguished,thereby improving the accuracy of FE *** reliability and effectiveness of FE simulation model largely depend on the accuracy of the simulation method,constitutive model,friction model,damage model in describing mesh element,the dynamic mechanical behavior of materials,the tool-chip-workpiece contact process and the chip formation *** this paper,the FE models of conventional and micro process variables are comprehensively and up-to-date reviewed for different materials and machining *** purpose is to establish a FE model that is more in line with the real cutting conditions,and to provide the possibility for optimizing the cutting process *** development direction of FE simulation of metal cutting process is discussed,which provides guidance for future cutting process modeling.

关键词： Conventional and micro scale Finite element simulation Metal cutting process Micro cutting Modeling

Insight into structural degradation of NCMs under extreme fast charging process

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Rare Metals 2024年第1期43卷 41-50页

作者： Yu Tang Xing-Yu wang Jin-Can Ren Bo-Wen Chen Zhi-Yong Huang Wei wang Ya-Lan Huang Bing-Hao Zhang Si Lan Zhang-Long He Qi Liu Hao He Department of Physics City University of Hong KongHong Kong 999077China Shenzhen Research Institute City University of Hong KongShenzhen 518057China College of Materials Science and Engineering Changsha University of Science&TechnologyChangsha 410114China

Lithium-ion batteries(LIBs)with extreme fast charging(XFC)capability are considered an effective way to alleviate range anxiety for electric vehicle(EV)*** to the high ionic and electronic conductivity of LiNi_(x)Co_(y)Mn_zO_(2)(x+y+z=1,NCM)cathodes,the inevitable Li plating of graphite in NCM|graphite cell is usually identified as a key bottleneck for XFC ***,the capacity decay mechanism of cathode materials under XFC has not been fully *** this work,three typical NCM cathode materials with different Ni fractions were chosen and their electrochemical performances under XFC associated with structural evolution were investigated.A faster capacity decay of NCMs under XFC conditions is observed,especially for Ni-rich ***-situ X-ray diffraction(XRD)reveals that the multiple caxis parameters appear at the high-voltage regions in Nirich NCMs,which is probably triggered by the larger obstruction of Li(de)***,NCMs with moderate Ni fraction also present a similar trend under XFC *** phenomenon is more detrimental to the structural and morphological stability,resulting in a faster capacity decay than that under low current *** work provides new insight into the degradation mechanism of NCMs under XFC conditions,which can promote the development of NCM cathode materials with XFC capability.

关键词： Lithium-ion batteries Ni fraction Extreme fast charging Structural evolution