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A pH-universal ORR catalyst with atomic Fe-heteroatom(N,S)sites for high-performance Zn-air batteries

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Nano Research 2023年第7期16卷 9416-9425页

作者： Le Li Na Li Jia-Wei Xia Shi-Long Zhou Xing-Yue Qian Feng-Xiang Yin Guo-Hong Dai Guang-Yu He hai-qun chen Key Laboratory of Advanced Catalytic Materials and Technology Advanced Catalysis and Green Manufacturing Collaborative Innovation CenterSchool of Petrochemical EngineeringChangzhou UniversityChangzhou 213164China Jiangsu Urban and Rural Construction Vocational College Changzhou 213147China

Developing innovative,easy-to-manufacture,and non-Pt-group-metal(non-PGM)electrocatalysts is essential for the highly efficient oxygen reduction reaction(ORR).Herein,we report a self-sacrificing post-synthetic strategy to synthesize highly loaded Fe-isolated single atoms anchored on the hierarchical porous N,S co-doped carbon matrix(Fe-SAs/S,N-C/rGO).The optimized Fe-SAs/S,N-C/rGO exhibits excellent ORR activity in the pH-universal range with half-wave potentials of 0.89,0.80,and 0.60 V in alkaline,acidic,and neutral media,comparable to the commercial Pt/C(0.85,0.81,and 0.64 V,respectively).The homemade liquid Zn-air battery(ZAB)with Fe-SAs/S,N-C/rGO as the cathode catalyst displays an open-circuit voltage(OCV)of~1.61 V,discharging specific capacity of 817.23 mAh·g^(-1),and long-term durability of~1865 cycles,outperforming those of the device with commercial Pt/C+RuO_(2)(1.49 V,657.32 mAh·g^(-1),and~120 cycles,respectively).Intriguingly,the corresponding flexible solidstate ZAB delivers satisfactory OCV,peak power density,foldability,and cycling stability at room temperature,as well as adaptability at a low temperature of -10℃.Besides,density functional theory(DFT)calculation reveals that the atomic FeN_(3)S moieties in Fe-SAs/S,N-C/rGO can cause charge redistribution and lower the binding strength of oxygen-containing intermediates,resulting in accelerated ORR kinetics and optimized catalytic *** work provides insights into experimental and theoretical guidance towards non-PGM electrocatalysts for efficient energy conversion.

关键词： heteroatom dopant single-atom electrocatalyst FeN_(3)S sites Zn-air battery density functional theory(DFT)study

Single-atom Fe-N_(5)catalyst for high-performance zinc-air batteries

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Nano Research 2022年第9期15卷 8056-8064页

作者： Le Li Yin-Juan chen Hao-Ran Xing Na Li Jia-Wei Xia Xing-Yue Qian Hui Xu Wei-Zuo Li Feng-Xiang Yin Guang-Yu He hai-qun chen Key Laboratory of Advanced Catalytic Materials and Technology Advanced Catalysis and Green Manufacturing Collaborative Innovation CenterSchool of Petrochemical EngineeringChangzhou UniversityChangzhou 213164China

Developing innovative and efficient non-precious-metal-group(non-PMG)electrocatalysts is crucial for the wide use of zinc-air batteries(ZABs).Herein,a single-atom catalyst(termed as Fe-N-C/rGO SAC)with unique five N-coordinated Fe(Fe-N_(5))centers is prepared by pyrolyzing the composite of zeolitic-imidazolate-frameworks-8(ZIF-8)and graphene oxide(GO).Specifically,the individual Fe site is stabilized by four equatorial and one axial N atoms donated by the N-doped carbon matrix and imidazole ring,respectively,thus forming an asymmetric electron depletion zone over the metal center,which can effectively promote the generation of reactive intermediates and accelerate the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)processes for *** rechargeable liquid ZAB with Fe-N-C/rGO catalyst exhibits an extremely high energy density(928.25 Wh·kg^(−1)),a remarkable peak power density(107.12 mW·cm^(−2)),and a long cycle life(400 h).Additionally,the corresponding flexible solid-state ZAB displays superior foldability and remarkable cycling *** work provides both experimental and theoretical guidance for rational design of non-PMG electrocatalyst-driven ZABs.

关键词： N-doped hierarchical porous carbon/rGO composite single-atom electrocatalyst five N-coordinated Fe(Fe-N_(5))singleatom sites zinc-air battery density functional theory(DFT)study

Significant effect of ordered micro-domain on cell boundary phase distribution and demagnetization curve squareness of Sm_(2)Co_(17)-type magnet

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Rare Metals 2024年第4期43卷 1724-1735页

作者： Zhuang Liu hai-chen Wu Chao-Yue Zhang Chao-qun Zhu Guo-Xin chen Huan-Ming Lu Ren-Jie chen Aru Yan CISRI&NIMTE Joint Innovation Center for Rare Earth Permanent Magnets Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo315201China University of Chinese Academy of Sciences Beijing100049China Analytical Center Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo315201China

Cu-rich cell boundary phase is difficult to precipitate evenly,resulting in a generally poor demagnetization curve squareness for Fe-rich Sm_(2)Co_(17)-type magnet,which is a key factor limiting the further improvement of magnetic energy *** this study,we report that nanoscale strip-like ordered micro-domains distributed in1:7H disordered matrix phase of the solid solution precursor is a new factor significantly affecting the precipitation and distribution of the cell boundary *** strip-like and continuous micro-twin structure with twin boundaries neatly perpendicular to the C-axis is observed after sintering *** solution treatment,sequential and long strip-like micro-twins gradually transform into disordered state along the basal plane,forming narrow disordered 1:7H(TbCu_(7)-type structure)phase between the separated strip-like ordered *** disordering transformation takes place via broken down of the long strip-like ordered micro-domains,which is accomplished by narrowing along the width direction followed by reduction of the ***,a new model revealing the effect of the ordered micro-domains on the formation of the cell boundary phase is *** boundaries enriched in Cu have already existed in the precursor with long strip-like ordered ***,the Cu-rich cell boundary phase acting as strong pinning centers cannot be precipitated homogeneously and distributed continuously after aging,resulting in a poor demagnetization curve squareness of Sm_(2)Co_(17)-type *** results indicate that significant broken down of the nanoscale ordered micro-domains in solution precursor is the key factor improving the distribution of cell boundary phase in Sm_(2)Co_(17)-type magnets.

关键词： Sm_(2)Co_(17) magnets Solution precursor Ordered micro-domains Disordering transformation Cellular structure

Very long wave infrared quantum dot photodetector up to 18μm

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Light(Science & Applications) 2024年第4期13卷 772-782页

作者： Xiaomeng Xue qun Hao Menglu chen School of Optics and Photonics Beijing Institute of TechnologyBeijing 100081China. Westlake Institute for Optoelectronics FuyangHangzhou 311421China. Physics Department Changchun University of Science and TechnologyChangchun 130022China

Colloidal quantum dots(CQDs)are of interest for optoelectronic devices because of the possibility of high-throughput solution processing and the wide energy gap tunability from ultraviolet to infrared *** may question about the upper limit on the CQD wavelength *** date,although the CQD absorption already reaches terahertz,the practical photodetection wavelength is limited within mid-wave *** figure out challenges on CQD photoresponse in longer wavelength,would reveal the ultimate property on these ***’s more,it motivates interest in bottom-up infrared photodetection with less than 10%cost compared with epitaxial growth semiconductor *** this work,developing a re-growth method and ionic doping modification,we demonstrate photodetection up to 18μm wavelength on HgTe *** liquid nitrogen temperature,the responsivity reaches 0.3 A/W and 0.13 A/W,with specific detectivity 6.6×108 Jones and 2.3×109 Jones for 18μm and 10μm CQD photoconductors,*** work is a step toward answering the general question on the CQD photodetection wavelength limitation.

关键词： quantum wave ultraviolet

A refined representation method of the particle size distribution curve based on grading entropy

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Particuology 2024年第5期88卷 302-311页

作者： Xing Li qun chen Zhaozhao Liu cheng Zhou chen Wang chen chen State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu610065China

The particle size distribution(PSD)curve is an important expression of the basic properties of the *** characteristic parameters such as median particle size D_(50),effective particle size D_(10),and some combinations of characteristic parameters can only represent some points of the PSD curve,failing to represent all information of the PSD *** this paper,a fraction characteristic parameter F that could reflect the fraction size variation of the PSD curve was introduced based on grading *** a new presentation method of the A-B-F three parameters was proposed for a refined representation of the PSD *** was found that the newly constructed model not only better represents the differences in the width of PSD curves but also has a higher sensitivity than the A-B two-parameter model proposed by Lő*** PSD curves with similar distributions,the new presentation method has a higher degree of discrimination than that of the D_(50)-C_(u)-C_(c) three-parameter or the four-parameter combination G_(c) proposed by ***,the application of this new method in describing the spatial nonuniformity distribution of depositions and predicting the soil hydraulic conductivity was *** research results can provide a reference for the refined representation of PSD curves.

关键词： Grading entropy Particle size distribution curve Refined representation

Data-driven active vibration control for helicopter with trailing-edge flaps using adaptive dynamic programming

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Chinese Journal of Aeronautics 2024年第6期37卷 151-166页

作者： Yu chen qun ZONG Xiuyun ZHANG Jinna LI School of Electrical and Information Engineering Tianjin UniversityTianjin 300072China School of Information and Control Engineering Liaoning Petrochemical UniversityFushun 113001China

The helicopter Trailing-Edge Flaps(TEFs)technology is one of the recent hot topics in morphing wing *** employing controlled deflection,TEFs can effectively reduce the vibration level of ***,designing specific vibration reduction control methods for the helicopters equipped with trailing-edge flaps is of significant practical *** paper studies the optimal control problem for helicopter-vibration systems with TEFs under the framework of adaptive dynamic programming combined with Reinforcement Learning(RL).Time-delay and disturbances,caused by complexity of helicopter dynamics,inevitably deteriorate the control performance of vibration *** solve this problem,a zero-sum game formulation with a linear quadratic form for reducing vibration of helicopter systems is presented with a virtual *** this context,an off-policy reinforcement learning algorithm is developed to determine the optimal control *** algorithm utilizes only vertical vibration load data to achieve a policy that reduces vibration,attains Nash equilibrium,and addresses disturbances while compensating for time-delay without knowledge of the dynamics of the helicopter *** effectiveness of the proposed method is demonstrated in a virtual platform.

关键词： Active control Adaptive dynamic program-ming Helicopter rotor Vibration control Zero-sum game

Strong Limit Theorems for Weighted Sums under the Sub-linear Expectations

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 862-874页

作者： Feng-xiang FENG Ding-cheng WANG qun-ying WU hai-wu HUANG School of Mathematics and Statistics Guilin University of TechnologyGuilin 541004China School of Mathematical Science University of Electronic Science and Technology of ChinaChengdu 611731China School of Science Guilin University of Aerospace TechnologyGuilin 541004China

In this article,we study strong limit theorems for weighted sums of extended negatively dependent random variables under the sub-linear *** establish general strong law and complete convergence theorems for weighted sums of extended negatively dependent random variables under the sub-linear *** results of strong limit theorems are more general than some related results previously obtained by Thrum(1987),Li et al.(1995)and Wu(2010)in classical probability space.

关键词： sub-linear expectation complete convergence complete moment convergence the maximal weighted sums

Cause analysis of expressway traffic accidents based on accident statistics of Hunan provincial expressway in 2012-2018

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Transportation Safety and Environment 2024年第1期6卷 83-92页

作者： Xinyu Liu Shengjun Huang qun chen Business school Foshan UniversityFoshan 528225GuangdongChina School of Traffic and Transportation Engineering Central South UniversityChangsha 410075HunanChina Hunan Provincial Expressway Traffic Police Station Law Enforcement DepartmentChangsha 410007HunanChina

Based on the 2012–2018 accident statistics on the Hunan Provincial Expressway in China,this paper analyses the proportion to which various factors contribute to accidents,as well as the trends over *** 2012 to 2018,the total number of general procedure handling accidents(*** accidents)increased first and then decreased,while the number of accidents and deaths per 1000 kilometres decreased year by *** total number of simple procedure handling accidents(*** accidents)increased year by year,but the number of accidents per 1000 kilometres remained relatively ***,fatigued driving,improper driving operation,failure to maintain a safe distance from the preceding vehicle and pedestrians entering the expressway are the main causes of general procedure handling *** to maintain a safe distance from the preceding vehicle as required and improper driving operation accounted for approximately 2/3 of the simple procedure handling *** view of the accidents caused by these factors,how to use law enforcement,education,science and technology and facilities construction to further reduce the occurrence of expressway traffic accidents is discussed.

关键词： expressway traffic accident cause analysis

Data-driven mapping-relationship mining between hardness and mechanical properties of dual-phase titanium alloys via random forest and statistical analysis

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Rare Metals 2024年第2期43卷 829-841页

作者： hai-Chao Gong qun-Bo Fan Hong-Mei Zhang Xing-Wang cheng Wen-Qiang Xie Kai chen Lin Yang Jun-Jie Zhang Bing-Qiang Wei Shun Xu School of Materials Science and Engineering Beijing Institute of TechnologyBeijing100081China National Key Laboratory of Science and Technology on Materials Under Shock and Impact Beijing100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing401135China Department of Mechanical and Materials Engineering University of Nebraska-LincolnLincolnNE68588USA

In order to accelerate the research on the property optimization of titanium alloy based on high-throughput methods,it is necessary to reveal the relationship between hardness and other mechanical properties which is still *** this work,taking Ti20C alloy as research object,almost all the microstructure of dual-phase titanium alloys were covered by traversing over 100 heat treatment ***,massive experiments including microstructure characterization and performance test were conducted,obtaining 51,590 pieces of microstructure data and 3591 pieces of mechanical property ***,based on large-scale data-driven technology,the quantitative mapping relationship between hardness and other mechanical properties was deeply *** results of random forest models showed that the correlation between hardness(H)and Charpy impact energy(A_(k))(or elongation,A)was hardly dependent on the microstructure types,while the relationship between H and tensile strength(R_(m))(or yield strength,R_(p0.2))was highly dependent on microstructure ***,combined with statistical analysis,it was found that the relationship between H and Ak(or A)were negatively ***,the relationship between H and strength was positively linear for equiaxed microstructure,and strength was linked to d^(−1/2)(d,equivalent circle diameter)ofα-grains in the form of classical Hall–Petch formula;but for other microstructures,the relationships were ***,the above rules were nearly the same in the rolling direction and transverse ***,a"four-quadrant partition map"between H and R_(p0.2)/R_(m) was established as a versatile material-screening tool,which can provide guidance for on-demand selection of titanium alloys.

关键词： Dual-phase titanium alloy Data-driven Hardness Mapping relationship