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Ultrahigh-brightness 50 MeV electron beam generation from laser wakefield acceleration in a weakly nonlinear regime

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Matter and Radiation at Extremes 2024年第3期9卷 4-10页

作者： Zhongtao Xiang Changhai Yu Zhiyong Qin Xuhui Jiao Jiahui Cheng Qiaoxuan Zhou Gatie Axi Jianghua Jie Ya Huang Jintan Cai Jiansheng Liu department of physics Shanghai Normal UniversityShanghai 200234China

We propose an efficient scheme to produce ultrahigh-brightness tens of MeV electron beams by designing a density-tailored plasma to induce a wakefield in the weakly nonlinear regime with a moderate laser energy of 120 *** this scheme,the second bucket of the wakefield can have a much lower phase velocity at the steep plasma density down-ramp than the first bucket and can be exploited to implement longitudinal electron injection at a lower laser intensity,leading to the generation of bright electron beams with ultralow emittance together with low energy ***-dimensional particle-in-cell simulations are carried out and demonstrate that high-quality electron beams with a peak energy of 50 MeV,ultralow emittance of28 nm rad,energy spread of 1%,charge of 4.4 pC,and short duration less than 5 fs can be obtained within a 1-mm-long tailored plasma density,resulting in an ultrahigh six-dimensional brightness B6D,n of2×1017 A/m2/0.1%.By changing the density parameters,tunable bright electron beams with peak energies ranging from 5 to 70 MeV,a small emittance of B0.1 mm mrad,and a low energy spread at a few-percent level can be *** bright MeV-class electron beams have a variety of potential applications,for example,as ultrafast electron probes for diffraction and imaging,in laboratory astrophysics,in coherent radiation source generation,and as injectors for GeV particle accelerators.

关键词： weakly nonlinear acceleration

Controllable synthesis of one-dimensional silicon nanostructures based on the dual effects of electro-deoxidation and the Kirkendall effect

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Nano Research 2024年第9期17卷 7814-7823页

作者： Jianxin Tu Shuo Yu Kui Hao Le Sun Ruicheng Bai Fangzhou Zhang Aijun Li Hong Liu Institute of Materials School of Materials Science and EngineeringShanghai UniversityShanghai 200444China department of Applied physics The Hong Kong Polytechnic UniversityKowloon 999077Hong KongChina Shaoxing institute of technology Shanghai UniversityShanghai 200444China

In this study,we successfully synthesized silicon nanotubes(Si-NTs)and silicon nanowires(Si-NWs)in a controllable manner using a catalyst-and template-free method through the direct electrolysis of SiO_(2)in a molten CaCl_(2)-CaO system,while also proposing a novel formation mechanism for ***-NWs are formed through electro-deoxidation when the cell voltage is within the range of CaO decomposition voltage and SiO_(2)decomposition *** subsequently adjusting the voltage to a value between the decomposition potentials of CaCl_(2)and CaO,in-situ electro-deoxidation of CaO takes place on the surface of the synthesized Si-NWs,leading to the formation of a Ca *** formation of Ca-Si diffusion couple leads to the creation of vacancies within the Si-NWs,as the outward diffusion rate of Si exceeds the inward diffusion rate of *** differential diffusion rates between Si and Ca in a diffusion couple exhibit an analogy to the Kirkendall *** vacancies gradually accumulate and merge,forming large voids,which ultimately result in the formation of hollow *** a subsequent dealloying process,the removal of the embedded calcium leads to the formation of *** the application of a carbon coating,the Si-NTs@C composite showcases a high initial discharge capacity of 3211 mAh·g^(-1)at 1.5 A·g^(-1)and exhibits exceptional long-term cycling stability,maintaining a capacity of 977 mAh·g^(-1)after 2000 cycles at 3.0 A·g^(-1).

关键词： silicon nanotubes silicon nanowires lithium-ion battery Kirkendall effect

Multi-source data integration and multi-scale modeling framework for progressive prediction of complex geological interfaces in tunneling

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Underground Space 2024年第2期15卷 1-25页

作者： Jingxiao Wang Peinan Li Xiaoying Zhuang Xiaojun Li Xi Jiang Jun Wu department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China College of Environmental Science and Engineering Donghua UniversityShanghai 201620China Institute of Photonics Department of Mathematics and PhysicsLeibniz University HannoverHannover 30167Germany department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong 100872China College of Civil Engineering Shanghai Normal UniversityShanghai 200233China

A reliable geological model plays a fundamental role in the efficiency and safety of mountain tunnel ***,regional models based on limited survey data represent macroscopic geological environments but not detailed internal geological characteristics,especially at tunnel portals with complex geological *** paper presents a comprehensive methodological framework for refined modeling of the tunnel surrounding rock and subsequent mechanics analysis,with a particular focus on natural space distortion of hard-soft rock interfaces at tunnel *** progressive prediction of geological structures is developed considering multi-source data derived from the tunnel survey and excavation *** improve the accuracy of the models,a novel modeling method is proposed to integrate multi-source and multi-scale data based on data extraction and potential field ***,a regional-scale model and an engineering-scale model are built,providing a clear insight into geological phenomena and supporting numerical *** addition,the proposed framework is applied to a case study,the Long-tou mountain tunnel project in Guangzhou,China,where the dominant rock type is *** results show that the data integration and modeling methods effectively improve model structure *** improved model’s calculation deviation is reduced by about 10%to 20%in the mechanical *** study contributes to revealing the complex geological environment with singular interfaces and promoting the safety and performance of mountain tunneling.

关键词： Mountain tunnel Geological modeling Multi-source data Progressive prediction Tunnel portals

A universal non-Hermitian platform for bound state in the continuum enhanced wireless power transfer

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Frontiers of physics 2024年第4期19卷 37-46页

作者： Haiyan Zhang Zhiwei Guo Yunhui Li Yaping Yang Yuguang Chen Hong Chen School of physics Science and Engineering Tongji UniversityShanghai 200092China department of Electrical Engineering Tongji UniversityShanghai 201804China

Non-Hermitian systems with parity–time(PT)-symmetry have been extensively studied and rapidly developed in resonance wireless power transfer(WPT).The WPT system that satisfies PT-symmetry always has real eigenvalues,which promote efficient energy ***,meeting the condition of PT-symmetry is one of the most puzzling *** power transfer under different transmission conditions is also a great *** state in the continuum(BIC)supporting extreme quality-factor mode provides an opportunity for efficient ***,we propose theoretically and demonstrate experimentally that BIC widely exists in resonance-coupled systems without PT-symmetry,and it can even realize more stable and efficient power transfer than PT-symmetric ***,BIC for efficient WPT is universal and suitable in standard second-order and even high-order WPT *** results not only extend non-Hermitian physics beyond PT-symmetry,but also bridge the gap between BIC and practical application engineering,such as highperformance WPT,wireless sensing and communications.

关键词： non-Hermitian physics parity-time asymmetry bound state in the continuum wireless power transfer

Phase Transition in a Dense Swarm of Self-Propelled Bots

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Fluid Dynamics & Materials Processing 2024年第8期20卷 1785-1798页

作者： Dmitry Bratsun Kirill Kostarev Applied physics department Perm National Research Polytechnic UniversityPerm614990Russia

Swarms of self-organizing bots are becoming important elements in various technical systems,which include the control of bacterial cyborgs in biomedical applications,technologies for creating new metamaterials with internal structure,self-assembly processes of complex supramolecular structures in disordered media,*** this work,we theoretically study the effect of sudden fluidization of a dense group of bots,each of which is a source of heat and follows a simple algorithm to move in the direction of the gradient of the global temperature *** show that,under certain conditions,an aggregate of self-propelled bots can fluidize,which leads to a second-order phase *** bots’program,which forces them to search for the temperature field maximum,acts as an effective buoyancy *** a consequence,one can observe a sudden macroscopic circulation of bots from the edge of the group to its center and back again,which resembles classical Rayleigh-Benard thermal *** the continuum approximation,we have developed a mathematical model of the phenomenon,which reduces to the equation of a self-gravitating porous disk saturated with an incompressible fluid that generates *** derive governing equations in the Darcy-Boussinesq approximation and formulate a nonlinear boundary value *** exact solution to the linearized problem for infinitesimal perturbations of the base state is obtained,and the critical values of the control parameter for the onset of the bot circulation are *** we apply weakly nonlinear analysis using the method of multiple time *** found that as the number of bots increases,the swarm exhibits increasingly complex patterns of circulation.

关键词： Active matter collective behavior self-organization convection

First-Principles Studies of Structural Evolutions in Cathode Materials LiMO_(2)(M=Co,Mn,Ni)

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Chinese physics Letters 2024年第10期41卷 129-136页

作者： Yufeng Sun Xin-Gao Gong Ji-Hui Yang Key Laboratory for Computational Physical Sciences(MOE) Department of PhysicsFudan UniversityShanghai 200433China shanghai Qizhi Institution Shanghai 200232China

We explore the structural evolutions of stoichiometric LiMO_(2)using the first-principles calculations combined with the cluster expansion *** automatically obtain the ground state structures of the stoichiometric LiMO_(2)by just considering the cation orderings in the quasi rock-salt structures and the following structural relaxations due to both the atomic size mismatches and the Jahn–Teller *** point out that,on the one hand,the cation orderings are mainly determined by the nearest,the second nearest,and the third nearest cation interactions and can be obtained from the‘phase diagram’we have built using the relative strengths of effective cluster interaction(ECI).On the other hand,the structural relaxations are dominated by the crystal field splitting(CFS)energies,i.e.,structures with larger CFS energies are more *** calculating the ECIs and CFS energies for various structures of LiMO_(2),we clearly show how ECI and CFS play roles in determining the structural evolution mechanism of these systems.

关键词： method. relaxation cluster

Polarization-dependent photoinduced metal–insulator transitions in manganites

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Science Bulletin 2024年第2期69卷 183-189页

作者： Lina Deng Weiye Zhang Hanxuan Lin Lifen Xiang Ying Xu Yadi Wang Qiang Li Yinyan Zhu Xiaodong Zhou Wenbin Wang Lifeng Yin Hangwen Guo Chuanshan Tian Jian Shen State Key Laboratory of Surface physics Institute for Nanoelectronic Devices and Quantum Computingand Department of PhysicsFudan UniversityShanghai 200433China shanghai Research Center for Quantum Sciences Shanghai 201315China Zhangjiang Fudan International Innovation Center Fudan UniversityShanghai 201210China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093China shanghai Branch CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum PhysicsShanghai 201315China

In correlated oxides,collaborative manipulation on light intensity,wavelength,pulse duration and polarization has yielded many exotic discoveries,such as phase transitions and novel quantum *** view of potential optoelectronic applications,tailoring long-lived static properties by light-induced effects is highly *** far,the polarization state of light has rarely been reported as a control parameter for this ***,we report polarization-dependent metal-to-insulator transition(MIT)in phaseseparated manganite thin films,introducing a new degree of freedom to control static ***,we observed giant photoinduced resistance jumps with striking features:(1)a single resistance jump occurs upon a linearly polarized light incident with a chosen polarization angle,and a second resistance jump occurs when the polarization angle changes;(2)the amplitude of the second resistance jump depends sensitively on the actual change of the polarization *** transmittance measurements reveal that the origin of the above phenomena is closely related to the coexistence of anisotropic *** results represent a first step to utilize light polarization as an active knob to manipulate static phase transitions,pointing towards new pathways for nonvolatile optoelectronic devices and sensors.

关键词： Metal-insulator phase transitions Polarization of light Electronic phase separation Selective domain controllability

Nondestructive Nonlinear Optical Microscopy Revealed the Blackening Mechanism of Ancient Chinese Jades

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Research 2024年第3期2023卷 391-399页

作者： Yaxin Chen Rong Wang Minbiao Ji State Key Laboratory of Surface physics and department of physics Human Phenome InstituteAcademy for Engineering and TechnologyKey Laboratory of Micro and Nano Photonic Structures(Ministry of Education)Yiwu Research Institute of Fudan UniversityFudan UniversityShanghai 200433China department of Cultural Heritage and Museology Fudan UniversityShanghaiChina

Jade is most valued in Chinese culture since ancient times. For unearthed jade artifacts, the alteration color resulting from weathering effects and human activities provides information for cultural heritage conservation, archaeology, and history. Currently, the noninvasive 3-dimensional characterization of jade artifacts with high chemical and spatial resolution remains challenging. In this work, we applied femtosecond pump–probe microscopy and second harmonic generation microscopy techniques to study the black alteration of an ancient jade artifact of the late Spring and Autumn period (546 to 476 BC). The direct cause of the “mercury alteration” phenomena was discovered to be the conversion of metacinnabar from buried cinnabar in the tomb. Furthermore, a 3-dimensional optical reconstruction of the black alteration was achieved, providing a high-resolution method for analyzing the blackening mechanism without the need of sample damage. Our approach opens up new opportunities to extract microscopic spatiochemical information for a broad range of alteration colors in jade artifacts.

关键词： pump Nonlinear buried

THE TRUNCATED EM METHOD FOR JUMP-DIFFUSION SDDES WITH SUPER-LINEARLY GROWING DIFFUSION AND JUMP COEFFICIENTS

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Journal of Computational Mathematics 2024年第1期42卷 178-216页

作者： Shounian Deng Chen Fei Weiyin Fei Xuerong Mao Key Laboratory of Advanced Perception and Intelligent Control of High-end Equipment Ministry of Educationand School of Mathematics-Physics and FinanceAnhui Polytechnic UniversityWuhu 241000China Business School University of Shanghai for Science and TechnologyShanghai 200093China department of Mathematics and Statistics University of StrathclydeGlasgow G11XHUK

This work is concerned with the convergence and stability of the truncated EulerMaruyama(EM)method for super-linear stochastic differential delay equations(SDDEs)with time-variable delay and Poisson *** constructing appropriate truncated functions to control the super-linear growth of the original coefficients,we present two types of the truncated EM method for such jump-diffusion SDDEs with time-variable delay,which is proposed to be approximated by the value taken at the nearest grid points on the left of the delayed *** first type is proved to have a strong convergence order which is arbitrarily close to 1/2 in mean-square sense,under the Khasminskii-type,global monotonicity with U function and polynomial growth *** second type is convergent in q-th(q<2)moment under the local Lipschitz plus generalized Khasminskii-type *** addition,we show that the partially truncated EM method preserves the mean-square and H∞stabilities of the true ***,we carry out some numerical experiments to support the theoretical results.

关键词： SDDEs Truncated EM method Time-variable delay Poisson jumps