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A Composite Ansatz for Calculation of Dynamical Structure Factor

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Chinese Physics Letters 2024年第1期41卷 92-103页

作者：张玉佩莫崇杰张平康炜 HEDPS Center for Applied Physics and Technologyand School of PhysicsPeking UniversityBeijing 100871China Beijing Computational science Research center Beijing 100193China Institute of applied Physics and Computational Mathematics Beijing 100088China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China

We propose an ansatz without adjustable parameters for the calculation of a dynamical structure *** ansatz combines the quasi-particle Green’s function,especially the contribution from the renormalization factor,and the exchange-correlation kernel from time-dependent density functional theory together,verified for typical metals and semiconductors from a plasmon excitation regime to the Compton scattering *** has the capability to reconcile both small-angle and large-angle inelastic x-ray scattering(IXS)signals with muchimproved accuracy,which can be used as the theoretical base model,in inversely inferring electronic structures of condensed matter from IXS experimental signals *** may also be used to diagnose thermal parameters,such as temperature and density,of dense plasmas in x-ray Thomson scattering experiments.

关键词： excitation inverse verified

Supporting IrO_(x) nanosheets on hollow TiO_(2) for highly efficient acidic water splitting

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Nano Research 2024年第8期17卷 6903-6909页

作者： Ge Yu Ruilong Li Yanmin Hu Xingen Lin Ze Lin Dongyang Wu Gongming Wang Xun Hong center of Advanced Nanocatalysis(CAN) Department of Applied ChemistryUniversity of Science and Technology of ChinaHefei 230026China

The efficiency of proton exchange membrane water electrolysis(PEM-WE)for hydrogen production is heavily dependent on the noble metal iridium-based ***,the scarcity of iridium limits the large-scale application of *** address this issue,it is promising to select an appropriate support because it not only enhances the utilization efficiency of noble metals but also improves mass transport under high ***,we supported amorphous IrO_(x) nanosheets onto the hollow TiO_(2) sphere(denoted as IrO_(x)),which demonstrated excellent performance in acidic electrolytic water ***,the annealed IrO_(x)catalyst at 150℃in air exhibited a mass activity of 1347.5 A·gIr^(−1),which is much higher than that of commercial IrO_(2) of 12.33 A·gIr^(−1) at the overpotential of 300 mV for oxygen evolution reaction(OER).Meanwhile,the annealed IrO_(x) exhibited good stability for 600 h operating at 10 mA·cm^(−2).Moreover,when using IrO_(x) and annealed IrO_(x) catalysts for water splitting,a cell voltage as low as 1.485 V can be achieved at 10 mA·cm^(−2).The cell can continuously operate for 200 h with negligible degradation of performance.

关键词： oxygen evolution reaction hydrogen evolution reaction amorphous IrO_(x) hollow TiO_(2) proton exchange membrane water electrolysis

Fracture mechanism of inclusions in thick plate center under tensile loading

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Journal of Iron and Steel Research International 2024年第5期31卷 1196-1209页

作者： Lei Hu Li-qin Zhang Feng Hu Guo-hong Zhang Kuan Zheng Collaborative Innovation center for Advanced Steels Wuhan University of Science and TechnologyWuhan430081HubeiChina Department of applied Physics Wuhan University of Science and TechnologyWuhan430081HubeiChina Analysis and Testing center Wuhan University of Science and TechnologyWuhan430081HubeiChina

Segregation of solute atoms in the center of thick plates of the tempered steel can cause an inhomogeneous structural transformation and generate micron-sized inclusions,which leads to lamellar tearing of thick plate and decreases the plasticity and *** formation and fragmentation mechanisms of micron-sized inclusions,like MnS and(Nb,Ti)C,in the center of thick plates were investigated by using thermodynamic calculations,finite element simulations,and electron backscatter diffraction characterization *** results show that micron-sized inclusions nucleate and grow in the liquid phase,and under tensile loading,they exhibit three fragmentation *** local stress during the fragmentation of inclusions is lower than the critical fracture stress of adjacent grains,and phase boundaries can effectively impede crack propagation into the *** existence of a low proportion of high-angle grain boundaries(58.1%)and high Kernel average misorientation value(0.534°)in the segregation band promotes inclusions fragmentation and crack *** difference in crack initiation and propagation direction caused by the morphology of inclusions and physical properties,as well as different matrix arrest abilities,is the main reasons for the diversity of inclusion fragmentation.

关键词： Thick plate Inclusion Finite element simulation Critical fracture stress Fracture mechanism

Curve Classification Based onMean-Variance Feature Weighting and Its Application

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Computers, Materials & Continua 2024年第5期79卷 2465-2480页

作者： Zewen Zhang Sheng Zhou Chunzheng Cao School of Mathematics and Statistics Nanjing University of Information Science and TechnologyNanjing210044China center for applied Mathematics of Jiangsu Province Nanjing University of Information Science and TechnologyNanjing210044China

The classification of functional data has drawn much attention in recent *** main challenge is representing infinite-dimensional functional data by finite-dimensional features while utilizing those features to achieve better classification *** this paper,we propose a mean-variance-based(MV)feature weighting method for classifying functional data or functional *** the feature extraction stage,each sample curve is approximated by B-splines to transfer features to the coefficients of the spline *** that,a feature weighting approach based on statistical principles is introduced by comprehensively considering the between-class differences and within-class variations of the *** also introduce a scaling parameter to adjust the gap between the weights of *** new feature weighting approach can adaptively enhance noteworthy local features while mitigating the impact of confusing *** algorithms for feature weighted K-nearest neighbor and support vector machine classifiers are both ***,the new approach can be well integrated into existing functional data classifiers,such as the generalized functional linear model and functional linear discriminant analysis,resulting in a more accurate *** performance of the mean-variance-based classifiers is evaluated by simulation studies and real *** results show that the newfeatureweighting approach significantly improves the classification accuracy for complex functional data.

关键词： Functional data analysis classification feature weighting B-splines

Constructing high coordination number of Ir-O-Ru bonds in IrRuO_(x)nanomeshes for highly stable acidic oxygen evolution reaction

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Nano Research 2024年第6期17卷 5073-5079页

作者： Ge Yu Ruilong Li Yida Zhang Xingen Lin Gongming Wang Xun Hong center of Advanced Nanocatalysis(CAN) Department of Applied ChemistryUniversity of Science and Technology of ChinaHefei 230026China National Synchrotron Radiation Laboratory(NSRL) University of Science and Technology of ChinaHefei 230029China

IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction(OER)catalysts,but breaking the trade-off between their activity and stability is an unresolved ***,addressing the issues of mass transport obstruction of IrRu bimetallic oxides under high current remains a challenge for the development of proton exchange membrane water electrolysis(PEM-WE).Herein,we prepared an IrRuO_(x)nanomeshes(IrRuO_(x)NMs)with high coordination number(CN)of Ir-O-Ru bonds in a mixed molten salt with high solubility of the Ir/Ru precursor.X-ray absorption spectroscopy analysis revealed that the IrRuO_(x)NMs possess high coordination number of Ir-O-Ru bonds(CNIr-O-Ru=5.6)with a distance of 3.18Å.Moreover,the nanomesh structures of IrRuO_(x)NMs provided hierarchical channels to accelerate the transport of oxygen and water,thus further improving the electrochemical ***,the IrRuO_(x)NMs as OER catalysts can simultaneously achieve high activity and stability with low overpotential of 196 mV to reach 10 mA·cm^(−2)and slightly increase by 70 mV over 650 h *** electrochemical mass spectrometry tests suggest that the preferred OER mechanism for IrRuO_(x)NMs is the adsorbent evolution mechanism,which is beneficial for the robust structural stability.

关键词： oxygen evolution reaction IrRuO_(x) Ir-O-Ru bonds two-dimensional(2D)nanomesh proton exchange membrane device mass transport

AstroPose:Astronaut pose estimation using a monocular camera during extravehicular activities

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science China(Technological sciences) 2024年第6期67卷 1933-1945页

作者： LIU ZiBin LI You WANG ChunHui LIU Liang GUAN BangLei SHANG Yang YU QiFeng College of Aerospace science and Engineering National University of Defense TechnologyChangsha410073China Key Laboratory of Human Factors Engineering China Astronaut Research and Training CenterBeijing100094China

With the completion of the Chinese space station,an increasing number of extravehicular activities will be executed by astronauts,which is regarded as one of the most dangerous activities in human space *** guarantee the safety of astronauts and the successful accomplishment of missions,it is vital to determine the pose of astronauts during extravehicular *** article presents a monocular vision-based pose estimation method of astronauts during extravehicular activities,making full use of the available observation ***,the camera is calibrated using objects of known structures,such as the spacesuit backpack or the circular handrail outside the space ***,the pose estimation is performed utilizing the feature points on the *** proposed methods are validated both on synthetic and semi-physical simulation experiments,demonstrating the high precision of the camera calibration and pose *** further evaluate the performance of the methods in real-world scenarios,we utilize image sequences of Shenzhou-13 astronauts during extravehicular *** experiments validate that camera calibration and pose estimation can be accomplished solely with the existing observation resources,without requiring additional complicated *** motion parameters of astronauts lay the technological foundation for subsequent applications such as mechanical analysis,task planning,and ground training of astronauts.

关键词： monocular camera astronaut pose estimation camera calibration

Privacy-Preserving Consensus-Based Distributed Economic Dispatch of Smart Grids via State Decomposition

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1250-1261页

作者： Wei Chen Guo-Ping Liu The authors are with the center for Control science and technology Southern University of Science and TechnologyShenzhen 518055China

This paper studies the privacy-preserving distributed economic dispatch(DED)problem of smart *** autonomous consensus-based algorithm is developed via local data exchange with neighboring nodes,which covers both the islanded mode and the grid-connected mode of smart *** prevent power-sensitive information from being disclosed,a privacy-preserving mechanism is integrated into the proposed DED algorithm by randomly decomposing the state into two parts,where only partial data is *** objective is to develop a privacy-preserving DED algorithm to achieve optimal power dispatch with the lowest generation cost under physical constraints while preventing sensitive information from being *** this end,a comprehensive analysis framework is established to ensure that the proposed algorithm can converge to the optimal solution of the concerned optimization problem by means of the consensus theory and the eigenvalue perturbation *** particular,the proposed autonomous algorithm can achieve a smooth transition between the islanded mode and the grid-connected ***,rigorous analysis is given to show privacy-preserving performance against internal and external ***,case studies illustrate the feasibility and validity of the developed algorithm.

关键词： preserving autonomous mode

Layered coordination polymer with two-dimensional covalent bismuth-organic networks:Semiconductor and lithium ion storage

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Nano Research 2024年第3期17卷 2181-2185页

作者： Mu-Qing Li Yulin Cao Lei Qin Hua Cheng Weimin Yang Zhouguang Lu School of Materials science and Environmental Engineering Shenzhen Polytechnic UniversityShenzhen 518055China Industrial training center Shenzhen Polytechnic UniversityShenzhen 518055China Department of Materials science and Engineering Southern University of Science and TechnologyShenzhen 518055China Department of Chemistry Southern University of Science and TechnologyShenzhen 518055China

Single crystals of a bismuth-based coordination polymer(CP)with carboxyl-thiol ligands,[Bi(C_(8)H_(2)O_(4)S_(2))(C2H8N)]n(Bi-DSBDC-DMA,DMBDC=2,5-disulfur-1,4-dicarboxylate,DMA=dimethylamine),have been successfully synthesized.X-ray diffraction analysis reveals that Bi-DSBDC-DMA possesses a layered structure,with two-dimensional(2D)Bi-DSBDC networks alternating with layers composed of dimethylamine *** material demonstrates semiconducting properties,featuring an optical bandgap of 2.2 eV and an electrical conductivity of 2×10^(-8) S/***,electrodes based on this material exhibit a capacity of 250 mAh/g after 200 cycles for lithium-ion storage.

关键词： bismuth layer coordination polymer(CP) semiconductor lithium ion storage

Exploring the Interplay between Local Chain Structure and Stress Distribution in Polymer Networks

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Chinese Journal of Polymer science 2024年第6期42卷 874-885页

作者： Jin-Tong Xue Yang Bai Li Peng Xian-Bo Huang Zhao-Yan Sun School of applied Chemistry and Engineering University of Science and Technology of ChinaHefei230026China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China National-certified Enterprise technology center Kingfa Science and Technology Co.Ltd.Guangzhou510663China

The mechanical behavior of polymer networks is intrinsically correlated with the local chain topology and chain *** this study,we delve into this relationship through the lens of coarse-grained molecular dynamics(CG-MD)*** aim is to illuminate the intricate interplay between local topology and stress distribution within polymer monomers,cross-linkers,and various components with distinct cross-link connections,thereby elucidating their collective impact on the mechanical properties of polymer *** mainly focus on how specific local structures contribute to the overall mechanical response of the *** particular,we employ local stress analysis to unravel the mechanics of these *** findings reveal the diverse responses of individual components,such as junctions,strands,cross-linkers between junctions,and dangling chain ends,when subjected to ***,we observe that these components exhibit varying degrees of deformation tolerance,underscoring the significance of their roles in determining the mechanical characteristics of the *** investigations highlight junctions as primary contributors to stress accumulation,and particles with higher local stress showing a stronger correlation between stress and Voronoi ***,our results indicate that both strands and cross-linkers between junctions exhibit heightened stress levels as strand lengths *** study enhances our understanding of the multifaceted factors governing the mechanical attributes of cross-linked polymer systems at the microstructural level.

关键词： Local chain structure Local stress Molecular dynamics simulation