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Electron vortex generations in photoionization of hydrogen atoms by circularly-polarized chirped attosecond pulses

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Communications in Theoretical Physics 2024年第1期76卷 111-118页

作者： Bingshuang Zhang Xiaoyu liu Fengzheng Zhu Liguang jiao Aihua liu Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China School of Mathematics and Physics Hubei Polytechnic UniversityHuangshi 435003China College of Physics Jilin UniversityChangchun 130012China Helmholtz-Institut Jena D-07743 JenaGermany State Key Laboratory of Transient Optics and Photonics Chinese Academy of SciencesXi'an 710119China

By numerically solving the time-dependent Schr?dinger equation and employing the analytical perturbative model,we investigated the chirp-induced electron vortex in the photoionization of hydrogen atoms by a pair of counter-rotating circularly polarized chirped attosecond extremely ultraviolet *** demonstrated that single-photon ionization of hydrogen atoms generates photoelectron momentum distributions(PMDs)with distinct helical vortex structures either with or without a time delay between two counter-rotating circularly polarized laser *** structures are highly sensitive to both the time delay between the pulses and their chirp *** analytical model reveals that the splitting of vortex spirals is caused by the sign changing of the chirp-induced frequency-dependent time *** showed that to obtain the counterpart of the PMD under a pair of counter-rotating circularly polarized chirped pulses,both chirp parameters and ordering of pulses need to be reversed.

关键词： photoionization ultrafast processes ultrafast dynamics electron vortex

Microstructural characterization and mechanical properties of(TiC+TiB)/TA15 composites prepared by an in-situ synthesis method

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China Foundry 2024年第2期21卷 168-174页

作者： Zhi-yong Zhang jiao-jiao Cheng Jia-qi Xie Shi-bing liu Kun Shi Jun Zhao Shenyang Research Institute of Foundry Co. Ltd.CAMShenyang 110022China National Key Laboratory of Advanced Casting Technologies Shenyang 110022China

Titanium matrix composites reinforced with ceramic particles are considered a promising engineering material due to their combination of high specific strength,low density,and high *** this study,the TA15-based composites reinforced with a volume fraction of 10% to 25%(TiB+TiC)were prepared using powder metallurgy and casting *** characterization and phase constitution were examined using optical microscopy(OM),scanning electron microscopy(SEM),and X-ray diffraction(XRD).In addition,the microhardness,room temperature(RT)and high temperature(HT)tensile properties of the composites were *** revealed that the reinforcements are distributed uniformly even in the composites with a high volume of TiB and ***,as the volume fraction exceeds 15%,TiB and TiC particles become coarsening and exhibit rod-like and dendritic-like *** increases gradually from 321.2 HV for the base alloy to a maximum of 473.3 HV as the reinforcement increases to 25vol.%.Tensile test results indicate that a reinforcement volume fraction above 20% is beneficial for enhancing tensile strength and yield strength at high temperatures,but it has an adverse effect on room temperature ***,if the reinforcement volume fraction is below 20%,it can improve high-temperature elongation when the temperature exceeds 600℃.

关键词： titanium matrix composites microstucture microhardness tensile properties in-situ synthesis

Energy budget of cold and hot gas-solid fluidized beds through CFD-DEM simulations

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Particuology 2024年第6期89卷 153-171页

作者： Lei Bi Yunpeng jiao Chunjiang liu Jianhua Chen Wei Ge School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

Direct energy budget is carried out for both cold and hot flow in gas–solid fluidization ***,the energy paths are proposed from thermodynamic *** consumption means total power input to the specific system,and it can be decomposed into energy retention and energy *** retention is the variation of accumulated mechanical energy in the system,and energy dissipation is the energy converted to heat by irreversible *** based on the Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)framework,different energy terms are quantified from the specific flow elements of fluid cells and particles as well as their interactions with the *** order to clarify the energy budget,it is important to identify which system is studied:the particle-fluid system or the particle *** the cold flow,the total energy consumption of the particle sub-system can well indicate the onset of bubbling and turbulent,while the variation of local energy consumption terms can reflect the evolution of heterogeneous *** the hot flow,different heat transfer mechanisms are analyzed and the solver is modified to reproduce the experimental *** impact of the heat transfer mechanisms and heat production on energy consumption is also *** proposed budget method has proven to be energy-conservative and easy to conduct,and it is hopeful to be applied to other multiphase flow systems.

关键词： Energy budget Gas-solid fluidization CFD-DEM Regime transition Heat transfer mechanism

Two-layer Lagrange-based relay network topology and trajectory design for solar system explorations

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Science China(Information Sciences) 2024年第6期67卷 342-358页

作者： Jun CAO Jian jiao Hao liu Rongxing LU Qinyu ZHANG Guangdong Provincial Key Laboratory of Aerospace Communication and Networking Technology Harbin Institute of Technology (Shenzhen) Faculty of Computer Science (FCS) University of New Brunswick

Exploration targeting outer planets and even the edge of the solar system is an emerging direction for the deep-space exploration in the next decades. To address this challenge, a novel two-layer Lagrangebased relay network topology is proposed in this study. Specifically, we utilize the Sun-Mars and Sun-Saturn Lagrange points(LPs) L4 and L5 to build a two-layer backbone relay network, which ensures continuous and high-efficiency communication capability for the exploration of the solar system. Furthermore, we utilize the planetary gravity assist and design the transfer trajectory of backbone relays with the help of planetary celestial body motion equations and Kepler's laws. Moreover, we conduct link budget analysis for multihop relay transmission under Gamma-Gamma distribution, shadowed Rician fading, and additive white Gaussian noise channels in several typical exploration scenarios and validate that the LP relays can effectively support future deep-space exploration missions.

关键词： deep-space communication Lagrangian points backbone relay network transfer trajectory relay selection

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Adaptive active inceptor design under shared control architecture for nonlinear pilot-induced oscillations

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Chinese Journal of Aeronautics 2024年第6期37卷 276-292页

作者： Xiaoyu liu Liguo SUN Wenqian TAN Shuting XU Junkai jiao School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China College of Engineering Beijing Forestry UniversityBeijing 100083China

This paper presents a Shared Control Architecture(SCA)between a human pilot and a smart inceptor for nonlinear Pilot Induced Oscillations(PIOs),e.g.,category II or III *** innovation of this paper is that an intelligent shared control architecture is developed based on the intelligent active inceptor technique,i.e.,Smart Adaptive Flight Effective Cue(SAFE-Cue).A deep reinforcement learning approach namely Deep Deterministic Policy Gradient(DDPG)method is chosen to design a gain adaptation mechanism for the SAFE-Cue *** doing this,the gains of the SAFE-Cue will be intelligently tuned once nonlinear PIOs triggered;meanwhile,the human pilot will receive a force cue from the SAFE-Cue,and will consequently adapting his/her control *** second innovation of this paper is that the reward function of the DDPG based gain adaptation approach is constructed according to flying *** the premise of considering failure situation,task completion qualities and pilot workload are also taken into ***,the proposed approach is validated using numerical simulation experiments with two types of scenarios:lower actuator rate limits and airframe *** Inceptor Peak Power-Phase(IPPP)metric is adopted to analyze the human-vehicle system simulation *** and analysis show that the DDPG based sharing control approach can well address nonlinear PIO problems consisting of Categories Ⅱ and Ⅲ PIO events.

关键词： Shared control architecture Activeinceptor Deep reinforcement learning Nonlinear pilot-induced oscillations Human-vehicle system

Human activity over natural inputs determines the bacterial community in an ice core from the Muztag ata glacier

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Science China Earth Sciences 2024年第5期67卷 1489-1499页

作者： Yongqin liu Nianzhi jiao Mukan JI Keshao liu Baiqing XU Bixi GUO Tandong YAO State Key Laboratory of Tibetan Plateau Earth System Resources and Environment(TPESRE)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Center for Pan-third Pole Environment Lanzhou UniversityLanzhou 730013China University of Chinese Academy of Sciences Beijing 100101China State Key Laboratory for Marine Environmental Science Xiamen UniversityXiamen 361102China

Ice core provides a valuable vertical timeline of past climates and anthropogenic *** proxies have been widely used in these studies,but there are few biological indicators *** address this gap,we investigated the bacterial community from a 74 m ice core of Muztag ata glacier on the Tibetan Plateau to link biological indicators with past climate and anthropogenic *** analyzing the portion of the ice core with environmental proxies available(corresponding to 1907 to 1991),we observed an increase in bacterial richness throughout the ice core,which was associated with higher NH_(4)^(+),an indicator of agricultural *** bacterial community was jointly determined by human activity,natural input,and air temperature,with a strong human influence after the ***,the relative abundance of animal gut-associated bacteria,including Aerococcaceae,Nocardiaceae,Muribaculaceae,and Lachnospiraceae,was associated with livestock number changes in the Central Asian *** with other bacterial lineages,they jointly explained 59.8%of the livestock number *** study provides quantitative evidence of the associations between bacterial indicators and past climate and human activities,highlighting the potential of using bacterial proxies for ice core studies.

关键词： Ice core of Muztag ata glacier Climate change and anthropogenic activity Biological indicator Gut-associated bacteria livestock number in the Central Asian region

Hydrochemical Characteristics and Evolution of Underground Brine in Lop Nur,Northwestern China

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Acta Geologica Sinica(English Edition) 2024年第3期98卷 786-800页

作者： BO Ying liu Chenglin jiao Pengcheng LU Fenglin ZHANG Hua MNR Key Laboratory of Metallogeny and Mineral Assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China

Lop Nur is located at the eastmost end of the Tarim Basin in Xinjiang,Northwestern *** study reviews the hydrochemical characteristics and evolution of underground brine in Lop Nur,based on analytical data from 429 water samples(mainly brine).It is found that in the NE-SW direction,from the periphery to the Luobei sub-depression,while the hydrochemical type varies from the sodium sulfate subtype(S)to the magnesium sulfate subtype(M),the corresponding brine in the phase diagram transfers from the thenardite phase(Then)area,through the bloedite phase(Blo),epsomite phase(Eps),picromerite phase(Picro),finally reaching the sylvite phase(Syl)*** for the degree of evolution,the sequence is the periphery

关键词： brine evolution isotope enrichment potassium Lop Nur

Theoretical screening of cooperative N-bridged dual-atom sites for efficient electrocatalytic nitrogen reduction with remolding insight

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Nano Research 2024年第4期17卷 3413-3422页

作者： Huimei Chen Yan Yang Chi jiao Zhiwen Zhuo Junjie Mao Yan liu Key Laboratory of Functional Molecular Solids Ministry of EducationCollege of Chemistry and Materials ScienceAnhui Normal UniversityWuhu 241002China

The electrocatalytic nitrogen reduction reaction(e-NRR)is a promising alternative method for the Haber–Bosch ***,it still faces many challenges in searching for high activity,stability,and selectivity catalysts and ascertaining the catalytic mechanism with complete ***,a series of graphene-based N-bridged dual-atom catalysts(M1-N-M2/NC)are systematically investigated via first-principle calculation and a high-throughput screening *** result unveils that N_(2) adsorption on M1-N-M2/NC in bridge-on adsorption mode can effectively break the scaling relationship on single-atom catalysts(SACs).Moreover,V-N-Ru/NC and V-N-Os/NC are systematically screened out as promising e-NRR catalysts,with extremely low limiting potentials of-0.20 and-0.18 V,***,the adsorption site competition between*N_(2) and*H,as well as the competitive twin reactions of hydrogen evolution reaction(HER)on intermediates(N_(n)H_(m))during the e-NRR process,is systematically evaluated to form a remodeling insight for the reactions in mechanism,and the e-NRR of new proposed dual-atom catalysts(DACs)is strategically optimized for its high-efficiency performance potential via our remolding insight in e-NRR *** work provides new ideas and insights for the design and mechanism of e-NRR catalysts and an effective strategy for rapidly screening highly efficient e-NRR catalysts.

关键词： nitrogen reduction dual-atom catalysts high-throughput screening hydrogen evolution reaction density functional theory calculations

New Hybrid CHP System Integrating Solar Energy and Exhaust Heat Thermochemical Synergistic Conversion with Dual-Source Energy Storage

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Journal of Thermal Science 2024年第3期33卷 970-984页

作者： QIN Yuanlong liu Taixiu LI Peijing ZHAO Kai jiao Fan PEI Gang liu Qibin Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei230027China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

For the efficient use of solar and fuels and to improve the supply-demand matching performance in combined heat and power(CHP)systems,this paper proposes a hybrid solar/methanol energy system integrating solar/exhaust thermochemical and thermal energy *** proposed system includes parabolic trough solar collectors(PTSC),a thermochemical reactor,an internal combustion engine(ICE),and hybrid storage of thermal and chemical energy,which uses solar energy and methanol fuel as input and outputs power and *** methanol thermochemical decomposition reaction,mid-and-low temperature solar heat and exhaust heat are upgraded to chemical energy for efficient power *** thermal energy storage(TES)stores surplus thermal energy,acting as a backup source to produce heat without emitting CO_(2).Due to the energy storage,time-varying solar energy can be used steadily and efficiently;considerable supply-demand mismatches can be avoided,and the operational flexibility is *** the design condition,the overall energy efficiency,exergy efficiency,and net solar-to-electric efficiency achieve 72.09%,37.65%,and 24.63%,*** fuel saving rate(FSR)and the CO_(2) emission reduction(ER_(CO_(2)))achieve 32.97%and 25.33%,*** research findings provide a promising approach for the efficient and flexible use of solar energy and fuels for combined heat and power.

关键词： hybrid energy system solar thermochemical exhaust heat energy storage operational flexibility