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An extended social force model on unidirectional flow considering psychological and behavioral impacts of hazard source

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Chinese physics B 2024年第2期33卷 567-576页

作者：邓凯丰李梦胡祥敏陈涛 Institute of Public Safety Research Department of Engineering PhysicsTsinghua UniversityBeijing 100084China Anhui Province key laboratory of Human Safety Hefei 230601China beijing key laboratory of Comprehensive Emergency Response Science Beijing 100084China

An accurate assessment of the evacuation efficiency in case of disasters is of vital importance to the safety design of buildings and street *** sources not only physically but psychologically affect the pedestrians,which may further alter their behavioral *** effect is especially significant in narrow spaces,such as corridors and *** study aims to integrate a non-spreading hazard source into the social force model following the results from a previous experiment and simulation,and to simulate unidirectional pedestrian flows over various crowd densities and clarity–intensity properties of the hazard *** integration include a virtual repulsion force from the hazard source and a decay on the social force *** simulations reveal(i)that the hazard source creates virtual bottlenecks that suppress the flow,(ii)that the inter-pedestrian push forms a stabilisation phase on the flow-density curve within medium-to-high densities,and(iii)that the pedestrians are prone to a less orderly and stable pattern of movement in low clarity–intensity scenarios,possibly with lateral collisions passing the hazard source.

关键词： evacuation social force model hazard source unidirectional pedestrian flow

Interface and mechanical degradation mechanisms of the silicon anode in sulfide-based solid-state batteries at high temperatures

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Chinese physics B 2024年第8期33卷 117-126页

作者：王秋辰黄昱力许晶禹习谦李泓陈立泉 key laboratory for Renewable Energy Beijing Key Laboratory for New Energy Materials and DevicesBeijing National Laboratory for Condensed Matter PhysicsInstitute of PhysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Huairou Division Institute of PhysicsChinese Academy of SciencesBeijing 101408China

Silicon(Si)is a competitive anode material owing to its high theoretical capacity and low electrochemical ***,the prospect of Si anodes in solid-state batteries(SSBs)has been proposed due to less solid electrolyte interphase(SEI)formation and particle ***,major challenges arise for Si anodes in SSBs at elevated *** this work,the failure mechanisms of Si-Li_(6)PS_(5)Cl(LPSC)composite anodes above 80℃are thoroughly investigated from the perspectives of interface stability and(electro)chemo-mechanical *** chemistry and growth kinetics of Lix Si|LPSC interphase are demonstrated by combining electrochemical,chemical and computational *** and/or Si–P compound formed at Lix Si|LPSC interface prove to be detrimental to interface stability at high *** the other hand,excessive volume expansion and local stress caused by Si lithiation at high temperatures damage the mechanical structure of Si-LPSC composite *** work elucidates the behavior and failure mechanisms of Si-based anodes in SSBs at high temperatures and provides insights into upgrading Si-based anodes for application in SSBs.

关键词： sulfide electrolytes silicon anodes interface stability degradation kinetics all-solid-state batteries

A compact X-band backward traveling-wave accelerating structure

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Nuclear Science and Techniques 2024年第5期35卷 13-29页

作者： Xian-Cai Lin Hao Zha Jia-Ru Shi Qiang Gao Fang-Jun Hu Qing-Zhu Li Huai-Bi Chen Department of engineering physics Tsinghua UniversityBeijing 100084China key laboratory of Particle and Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated *** proposed a compact VHEE facility based on an X-band high-gradient high-power *** this study,we investigated and realized the first X-band backward traveling-wave(BTW)accelerating structure as the buncher for a VHEE facility.A method for calculating the parameters of single cell from the field distribution was introduced to simplify the design of the BTW ***-domain circuit equations were applied to calculate the transient beam parameters of the buncher in the unsteady state.A prototype of the BTW structure with a thermionic cathode-diode electron gun was designed,fabricated,and tested at high power at the Tsinghua X-band high-power test *** structure successfully operated with 5-MW microwave pulses from the pulse compressor and outputted electron bunches with an energy of 8 MeV and a pulsed current of 108 mA.

关键词： Backward traveling-wave accelerating structure Equivalent circuit model High-power test Very high-energy electron radiotherapy

Numerical Study on the Aerodynamic and Fluid−Structure Interaction of An NREL-5MW Wind Turbine

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China Ocean engineering 2024年第3期38卷 363-378页

作者： ZHAO Mi YU Wan-li WANG Pi-guang QU Yang DU Xiu-li key laboratory of Urban Security and Disaster engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China State key laboratory of Bridge engineering Safety and Resilience Beijing University of TechnologyBeijing 100124China

A 5-MW wind turbine has been modeled and analyzed for fluid-structure interaction and aerodynamic *** this study, a full-scale model of a 5-MW wind turbine is first developed based on a computational fluid dynamics(CFD) approach, in which the unsteady, noncompressible Reynolds Averaged Navier-Stokes(RANS) method is used. The main focus of the study is to analyze the tower shadow effect on the aerodynamic performance of the wind turbine under different inlet flow conditions. Subsequently, the finite element model is established by considering fluid/structure interactions to study the structural stress, displacement, strain distributions and flow field information of the structure under the uniform wind speed. Finally, the fluid-structure interaction model is established by considering turbulent wind and the tower shadow effect. The variation rules of the dynamic response of the one-way and two-way fluid-structure interaction(FSI) models under different wind speeds are analyzed, and the numerical calculation results are compared with those of the centralized mass model. The results show that the tower shadow effect and structural deformation are the main factors affecting the aerodynamic load fluctuation of the wind turbine, which in turn affects the aerodynamic performance and structural stability of the blades. The structural dynamic response of the coupled model shows significant similarity, while the structural displacement response of the former exhibits less fluctuation compared with the conventional centralized mass model. The one-way fluid-structure interaction(FSI)model shows a higher frequency of stress-strain and displacement oscillations on the blade compared with the two-way FSI model.

关键词： computational fluid dynamics methods(CFD) tower shadow effect aerodynamic performance fluidstructure interaction space flow field

Probing phase transition of band topology via radiation topology

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Photonics Research 2024年第6期12卷 1150-1157页

作者： CHANG-YIN JI WENZE LAN PENG FU GANG WANG CHANGZHI GU YELIANG WANG JIAFANG LI YUGUI YAO BAOLI LIU key laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE) Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic Systemsand School of PhysicsBeijing Institute of TechnologyBeijing 100081China School of Integrated Circuits and Electronics MIIT Key Laboratory for Low-Dimensional Quantum Structure and DevicesBeijing Institute of TechnologyBeijing 100081China beijing National laboratory for Condensed Matter physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing 100190China CAS Center for Excellence in Topological Quantum Computation CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing 100190China

Topological photonics has received extensive attention from researchers because it provides brand new physical principles to manipulate *** topology is characterized using the Berry phase defined by Bloch *** now,the scheme for experimentally probing the topological phase transition of band topology has always been relatively lacking in topological ***,radiation topology can be aroused by the far-field polarization singularities of Bloch states,which is described by the Stokes *** such two types of topologies are both related to Bloch states on the band structures,it is rather surprising that their development is almost ***,in optical analogs of the quantum spin Hall effects(QSHEs)and Su-Schrieffer-Heeger model,we reveal the correlation between the phase transition of band topology and radiation topology and then demonstrate that the radiation topology can be employed to study the band topological *** experimentally demonstrate such an intriguing phenomenon in optical analogs of *** findings not only provide an insightful understanding of band topology and radiation topology,but also can serve as a route to manipulate light.

关键词： transition topology topological

Comparison of Measurements for Enhanced Diffusion Problem in Chemical Reaction Systems

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Chinese Journal of Chemistry 2024年第14期42卷 1659-1664页

作者： Ah-Young Jee Ziyang Wen Huan Wang beijing National laboratory for Molecular Sciences College of Chemistry and Molecular EngineeringBeijing Key Laboratory of Polymer Chemistry&Physics of Ministry of EducationPeking UniversityBeijing100871 China

The problem of molecular diffusion in the soup of chemical reactions attracts mounting interest across fields ranging from chemistry to biophysics to material *** reactions involve bond breakup and formation,whose time scale is typically on the orders of fs to ps,while molecular diffusion occurs at time scales ofμs to *** two processes are often considered orthogonal,given the vastly different *** serial results show that the enzyme's diffusion is enhanced in a substrate-dependent manner,which was further extended to small molecule reaction systems,challenging this classical ***,the results from different groups using different techniques do not quantitatively agree,and a general mechanism is yet to be *** summarize experimental studies on diffusion problems and seek to reconcile the interpretation with understanding the limits of measurement tools and the chemical nature of reaction *** molecular diffusion in chemical reactions will provide fresh thoughts in designing chemical systems such as molecular machines that harvest work at the nanoscale in a controllable manner.

关键词： Molecular diffusion Chemical reactions Enzyme reactions Active matter Diffusion measurements Single-molecule studies Fluorescence Time-resolved spectroscopy

Formation of mesophase microbeads from bulk mesophase pitch induced by fullerene

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新型炭材料（中英文） 2024年第4期39卷 645-654页

作者： CHEN Wen-sheng LIU Lan-tao WANG Zheng DUAN Chun-feng ZHANG Xing-wei MA Zhao-kun CHEN Xiao-hong SONG Huai-he State key laboratory of Chemical Resource engineering Beijing Key Laboratory of Electrochemical Process and Technology for MaterialsBeijing Uni-versity of Chemical TechnologyBeijing 100029China

A transformation of naphthalene-based coalescenced mesophase pitch(NMP)to mesophase microbeads was achieved by heating a mixture of NMP and fullerene(C_(60)).This is different from the conventional process of the liquid-phase carbonization of isotropic pitch to the emergence of carbon microbeads in the matrix and finally their growth to form a 100%anisotropic bulk meso-phase,but rather a reverse *** effects of C_(60) loading and reaction temperature on the morphological transformation of mesophase were investigated by polarizing optical and scanning electron *** physical changes in the NMP induced by C_(60) were characterized by thermogravimetric analysis,Fourier transform infrared spectroscopy,X-ray diffractometry and Raman *** results show that the coalesced NMP can be converted to a spherical type at 300-320℃ with the addition of 5%C_(60),and the size of the mesophase microbeads increases with increasing ***,a model is established to ex-plain the unique induction effect of C_(60) in the transformation *** work makes the morphological transformation of MP con-trollable,and provides a new idea for the understanding and research of mesophase pitch.

关键词： Reversible transformation Fullerene induction mechanism Mesophase texture π-electron-induced effect Mesophase microbeads

Self-assembly Induced by Complexation of Diblock Copolyelectrolytes and Oppositely Charged Homopolymers

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Chinese Journal of Polymer Science 2024年第9期42卷 1321-1332,I0006页

作者： Ling Zhao Zhi-Yuan Yin Jia-Di Jiang Er-Qiang Chen Shuang Yang beijing National laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of EducationCenter for Soft Mater Science and EngineeringCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China beijing National laboratory for Molecular Sciences College of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China

We investigate the solution self-assembly of a mixture of positively charged homopolymers and AB diblock copolymers,in which the A blocks are negatively charged,and the B blocks are *** electrostatic complexation between oppositely charged polymers drives the formation of many ordered *** microstructures and phase diagrams are calculated using self-consistent field theory(SCFT)based on an ion-pair model with an equilibrium constant K to characterize the strength of binding between positively and negatively charged *** effects of the charge ratio,representing the ratio of charges from the homopolymer over all charges from polymers in the system,on the ordered structure are systematically studied,both for hydrophobic and hydrophilic A *** charge ratio plays an important role in determining the phase boundaries in the phase diagram of salt concentration versus polymer *** also provide information about the varying tendency of the domain spacing and core size of the spherical phase when the charge ratio is changed,and the results are in good agreement with *** studies provide a deep understanding of the self-assembled microstructures of oppositely charged diblock copolymer-homopolymer systems.

关键词： Self-assembly Polyelectrolyte complexation Self-consistent field theory Ion-pair

Analytical Solution and Simplified Formula for Added Mass of Horizontal and Vertical Motions of Truncated Cylinders Under Earthquake Action

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China Ocean engineering 2024年第1期38卷 54-67页

作者： WANG Pi-guang LYU Si-yu QU Yang ZHAO Mi DU Xiu-li State key laboratory of Bridge engineering Safety and Resilience Beijing University of TechnologyBeijing 100124China key laboratory of Urban Security and Disaster engineering of Ministry of Education Beijing University of Tech-nologyBeijing 100124China

This paper investigates the hydrodynamic characteristics of floating truncated cylinders undergoing horizontal and vertical motions due to earthquake excitations in the finite water *** governing equation of the hydrodynamic pressure acting on the cylinder is derived based on the radiation theory with the inviscid and incompressible *** governing equation is solved by using the method of separating variables and analytical solutions are obtained by assigning reasonable boundary *** analytical result is validated by a numerical model using the exact artificial boundary simulation of the infinite *** main variation and distribution characteristics of the hydrodynamic pressure acting on the side and bottom of the cylinder are analyzed for different combinations of wide-height and immersion *** added mass coefficient of the cylinder is calculated by integrating the hydrodynamic pressure and simplified formulas are proposed for engineering *** calculation results show that the simplified formulas are in good agreement with the analytical solutions.

关键词： earthquake hydrodynamic pressure truncated cylinder added mass simplified formula