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Chinese Physics B 2025年第2期34卷 454-461页

作者： Cancan Shao Houbing Huang Beijing institute of Technology Zhuhai Beijing Institute of TechnologyZhuhai 519088China School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Advanced Research institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China

Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effective Hamiltonian method in conjuction with the phase-field model, we have successfully reproduced the thermal hysteresis observed in ferroelectric materials during phase transitions. The computational results regarding the electrocaloric effect from these two different computational scales closely align with experimental measurements. Furthermore, we analyze how the first-order ferroelectric phase transition gradually diminishes with an increasing applied electric field, exhibiting characteristics of second-order-like phase transition. By employing the characteristic parameters of thermal hysteresis, we have established a pathway for calculations across different computational scales, thereby providing theoretical support for further investigations into the properties of ferroelectric materials through concurrent multiscale simulations.

关键词： ferroelectric phase transition thermal hysteresis multiscale simulation effective Hamiltonian phase-field model

Distribution and mapping of temperate savanna in the sandy lands of eastern China

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Science China Earth Sciences 2025年第1期68卷 128-141页

作者： Xiaoya LI Feng WANG Tao DUAN Kaijie YANG Bin YANG Chunmei WANG Xin TIAN Qi LU institute of Ecological Conservation and Restoration Institute of Desertification StudiesChinese Academy of ForestryBeijing100091China institute of Desertification Institute of Desertification StudiesChinese Academy of ForestryBeijing100091China institute of Great Green Wall Bayan Nur015200China Satellite Application Centre for Ecology and Environment MEEBeijing100094China institute of Microelectronics Chinese Academy of SciencesBeijing100029China Aerospace Information Research institute Chinese Academy of SciencesBeijing100094China institute of Forest Resource Information Techniques Chinese Academy of ForestryBeijing100091China

Savannas are distributed globally across various *** perform a significant socioeconomic role in regulating net primary productivity and the terrestrial carbon *** to the high spatial heterogeneity induced by the mixed distribution of trees and grasses,current global land-cover classification maps often classify savannas as forests or grasslands Temperate savannas in China cover a vast area,yet their spatial patterns and extent remain poorly *** study developed a novel remote sensing temperate savannas mapping method by integrating very high-resolution(VHR)unmanned aerial vehicle(UAV)and GF-6 satellite imagery based on the vegetation structure characteristics of temperate savannas using the FAO definition of *** and validation datasets were collected from VHR UAV imagery covering the main temperate savannah types with a ground area of 1818 *** fractional woody vegetation cover(FWVC)and fractional herbaceous vegetation cover(FHVC)in temperate savannas were estimated by integrating Classification and Regression Tree and Random Forest *** current distribution of temperate savannas in the Horqin and Otindag Sandy Lands of Eastern China was mapped to a unit area of 0.5 *** root-mean-square error(RMSE)values for the FWVC and FHVC models were 10.69%and 11.67%,and the R^(2)values were 0.66 and 0.63,*** assessment indicated that the new temperate savanna map had high identification accuracy,with a Kappa coefficient of 0.70,overall accuracy of 0.88,and average accuracy of *** savannas in the sandy lands of eastern China were primarily distributed in the northern Horqin Sandy Land the central and eastern regions of the Otindag Sandy Land,and the transition zone from the southern slopes of the Greater Khingan Mountains to the plains,covering a total area of 3.27×10^(6)*** main savannah types were elm,oak/maple,and shrub *** savannas were widely distributed in the Otindag Sandy Land a

关键词： Temperate savanna UAV imagery GF-6 Fractional woody vegetation cover Fractional herbaceous vegetation cover Machine learning

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Output Consensus of Heterogeneous Linear MASs via Adaptive Event-Triggered Feedback Combination Control

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IEEE/CAA Journal of Automatica Sinica 2025年第1期12卷 285-287页

作者： Shuo Yuan Chengpu Yu Jian Sun the School of Automation Beijing Institute of Technology the Beijing institute of Technology Chongqing Innovation Center

Dear Editor,This letter studies output consensus problem of heterogeneous linear multiagent systems over directed graphs. A novel adaptive dynamic event-triggered controller is presented based only on the feedback combination of the agent's own state and neighbors' output,which can achieve exponential output consensus through intermittent communication. The controller is obtained by solving two linear matrix equations, and Zeno behavior is excluded.

关键词： Directed graphs

Extraction of rare earth elements from neodymium(NdFeB) magnet scrap using magnesium halides

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Journal of Rare Earths 2025年第2期43卷 371-376页

作者： Sung Gue Heo Jae Yeol Yang Soong Ju Oh Seok-Jun Seo Mi Hye Lee Kyoung-Tae Park Korea institute for Rare Metals Korea Institute of Industrial Technology Department of Materials Science and Engineering Korea University

The demand for neodymium（NdFeB） permanent magnets for electric vehicles and eco-friendly generators is ***,NdFeB magnets contain rare earth elements（REEs）,which are limited in *** this study,we performed an exchange reaction between magnesium halides（fluoride and chloride） and waste NdFeB scrap and then compared the characteristics of the extracted halides *** compositions of the ternary Mg fluoride（LiF:NaF:MgF2=50:40:10 in mole ratio） and chloride（LiCl:NaCl:MgCl2=10:50:40 in mole ratio） salts were thermodynamically determined for achieving low eutectic *** reactions between the NdFeB scrap powder（1-2 mm） and Mg halide salts were carried out at 1073 and 873 K for the fluoride and chloride systems,respectively,in an argon *** the reaction,we separated Nd halide from the residual salt and evaluated the Ndextraction *** phase formation of the salt was analyzed using X-ray diffraction（XRD）,and the extraction rate of Nd was analyzed using inductively coupled plasma optical emission spectroscopy（ICPOES）.Nd was extracted in the form of Nd halide（NdF3or NdCl3）,and the extraction rates in the fluoride and chloride systems are 98.64% and 84.59%,***,the fluoride system is more effective than the chloride system for Nd *** study provides a comprehensive comparative analysis of the effectiveness of fluo ride and chlo ride systems in extracting REEs from NdFeB magnet *** study findings can be used to develop an effective method for recycling magnet scraps.

关键词： Fluoride system Magnesium halide Metal-scrap recycling Nd extraction Neodymium magnet Rare earth elements

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Boosting bidirectional sulfur conversion enabled by introducing boron-doped atoms and phosphorus vacancies in Ni_(2)P for lithium-sulfur batteries

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Journal of Energy Chemistry 2025年第1期100卷 760-769页

作者： Lin Peng Yu Bai Hang Li Meixiu Qu Zhenhua Wang Kening Sun Advanced Research institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Chemical Power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China

Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox ***,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur *** study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur ***,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation ***,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.

关键词： B-doped atoms P vacancies Nickel phosphide Bidirectional sulfur conversion Lithium-sulfur batteries

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Achievable dual-strategy to stabilize Li-rich layered oxide interface by a one-step wet chemical reaction towards long oxygen redox reversibility

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Journal of Energy Chemistry 2025年第2期101卷 120-131页

作者： Bin He Yujie Dai Shuai Jiang Dawei Chen Xilong Wang Jie Song Dan Xiao Qian Zhao Yan Meng Wei Feng School of Mechanical Engineering Chengdu University Chongqing institute of Metrology and Quality Inspection institute of New Energy and Low-Carbon Technology Sichuan University

Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structu ral degradation of high energy-density Li-rich layered oxide（LLO）,leading to voltage and capacity ***,the dual-strategy of Cr,B complex coating and local gradient doping is simultaneously achieved on LLO surface by a one-step wet chemical reaction at room *** functional theory（DFT） calculations prove that stable B-O and Cr-O bonds through the local gradient doping can significantly reduce the high-energy O 2p states of interfacial lattice O,which is also effective for the near-surface lattice O,thus greatly stabilizing the LLO surface,Besides,differential electrochemical mass spectrometry（DEMS） indicates that the CrxB complex coating can adequately inhibit oxygen release and prevents the migration or dissolution of transition metal ions,including allowing speedy Li+migration,The voltage and capacity fading of the modified cathode（LLO-CrB） are adequately suppressed,which are benefited from the uniformly dense cathode electrolyte interface（CEI） composed of balanced organic/inorganic ***,the specific capacity of LLO-CrB after 200 cycles at 1C is 209.3 mA h g-1（with a retention rate of 95.1%）.This dual-strategy through a one-step wet chemical reaction is expected to be applied in the design and development of other anionic redox cathode materials.

关键词： Interfacial oxygen Lithium-rich layered oxide cathode Local gradient doping One-step wet chemical reaction Surface coating

An asymmetrically variable wingtip anhedral angles morphing aircraft based on incremental sliding mode control:Improving lateral maneuver capability

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Chinese Journal of Aeronautics 2025年第1期38卷 455-470页

作者： Xiaodong LIU Yong XU Jianqiao LUO School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Chongqing Innovation Center Beijing Institute of TechnologyChongqing 401120China

This paper presents the design of an asymmetrically variable wingtip anhedral angles morphing aircraft,inspired by biomimetic mechanisms,to enhance lateral maneuver ***,we establish a lateral dynamic model considering additional forces and moments resulting during the morphing process,and convert it into a Multiple Input Multiple Output(MIMO)virtual control system by importing virtual ***,a classical dynamics inversion controller is designed for the outer-loop system.A new Global Fast Terminal Incremental Sliding Mode Controller(NDO-GFTISMC)is proposed for the inner-loop system,in which an adaptive law is implemented to weaken control surface chattering,and a Nonlinear Disturbance Observer(NDO)is integrated to compensate for unknown *** whole control system is proven semiglobally uniformly ultimately bounded based on the multi-Lyapunov function ***,we consider tracking errors and self-characteristics of actuators,a quadratic programmingbased dynamic control allocation law is designed,which allocates virtual control inputs to the asymmetrically deformed wingtip and *** dynamic models are incorporated to ensure physical realizability of designed allocation ***,comparative experimental results validate the effectiveness of the designed control system and control allocation *** NDO-GFTISMC features faster convergence,stronger robustness,and 81.25%and 75.0%reduction in maximum state tracking error under uncertainty compared to the Incremental Nonlinear Dynamic Inversion Controller based on NDO(NDO-INDI)and Incremental Sliding Mode Controller based on NDO(NDO-ISMC),*** design of the morphing aircraft significantly enhances lateral maneuver capability,maintaining a substantial control margin during lateral maneuvering,reducing the burden of the rudder surface,and effectively solving the actuator saturation problem of traditional aircraft during lateral maneuvering.

关键词： Morphing aircraft Lateral maneuver capability Incremental sliding mode control Multi-Lyapunov function method Control theory Control allocation law

A Three-Dimensional SPH Simulation of Lander Footpad Impact on a Lunar Regolith Bed

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Computer Modeling in Engineering & Sciences 2025年第2期142卷 2045-2066页

作者： Wanqing Yuan Huiying Xie Can Huang Xiaoliang Wang Qingquan Liu Department of Mechanics School of Aerospace EngineeringBeijing Institute of TechnologyBeijing100081China institute of Computational Aerodynamics China Aerodynamics Research and Development CenterMianyang621000China institute of Large Structures for Advanced Industrial Equipment Beijing Institute of TechnologyZhuhai519088China

Landing spacecraft experience significant impact forces during landing,resulting in large deformation and failure in the soil surface,which severely affects landing safety and *** paper establishes a smoothed particle hydrodynamics(SPH)model based on the theory of soil elastoplastic constitutive relations to describe the process of a lander’s footpad impacting lunar regolith *** model can provide engineering indices such as impact load and penetration depth,and illustrate the large deformation and crater characteristics of the regolith.A detailed analysis of the response of the footpad and lunar regolith during landing reveals that the process can be broadly divided into two stages of rapid penetration and oscillatory ***,there are significant similarities in the landing process under different landing velocities and footpad *** research investigates the large deformation and crater characteristics of the lunar regolith *** results demonstrate two failure modes in the *** the impact of a footpad with a smaller mass,the final failure surface of the regolith exhibits a bowl-shaped profile with a uniformly open *** contrast,under the impact of a footpad with a larger mass,the final failure surface of the regolith presents an urn-shaped profile with a large abdomen and a small ***,the impact craters in both scenarios show a bowl-like *** cases of high-velocity impacts,the impact crater exhibits obvious blocky spalling on its *** SPH model developed in this study can be applied to predict the large deformation and failure response of lunar soil under the impact of rigid structures as well as the impact load and penetration *** effectively predicts the dynamic response of the landing process,which is expected to provide a reference for engineering design.

关键词： SPH footpad load lunar regolith impact crater

Status analysis on sputtering and erosion evaluation methods of ion optic systems

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Chinese Journal of Aeronautics 2025年第1期38卷 254-270页

作者： Long MIAO Tongxun YANG Zhengxi ZHU Chang LU Zhiwen WU Ningfei WANG School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Chongqing Innovation Center Beijing Institute of TechnologyChongqing 404100China Advanced Aerospace Power and Energy Research Center Beijing Institute of TechnologyZhuhai 519088China

In the past few decades,ion engines have been widely used in deep-space propulsion and satellite *** aim of extending the thruster lifetime is still one of the most important parts during the design stage of ion *** one of the core components of ion engine,the grid assembly of ion optic systems may experience long-term ion sputtering in extreme electro-thermal environments,which will eventually lead to its structural and electron-backstreaming *** this paper,the current studies of the grid assembly erosion process are systematically analyzed from the aspects of sputtering damage process of grid materials,numerical simulations,and measurements of erosion characteristics of grid *** advantages and disadvantages of various erosion prediction models are highlighted,and the key factors and processes affecting the prediction accuracy of grid assembly erosion patterns are *** different types of experimental methods of grid assembly erosion patterns are *** analysis in this paper is of great importance for selecting the sputter-resistant grid materials,as well as establishing the erosion models and measurement methods to accurately determine the erosion rate and failure modes of grid ***,the working conditions and structure parameters of ion optic systems could be optimized based on erosion models to promote the ion engine lifetime.

关键词： Electric propulsion Ion optic systems Sputtering yield Erosion characteristics Erosion pattern measurement Lifetime evaluation

Improving Model Chain Approaches for Probabilistic Solar Energy Forecasting through Post-processing and Machine Learning

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Advances in Atmospheric Sciences 2025年第2期42卷 297-312页

作者： Nina HORAT Sina KLERINGS Sebastian LERCH institute of Statistics Karlsruhe Institute of TechnologyKarlsruhe 76185Germany Heidelberg institute for Theoretical Studies Heidelberg 69118Germany

Weather forecasts from numerical weather prediction models play a central role in solar energy forecasting,where a cascade of physics-based models is used in a model chain approach to convert forecasts of solar irradiance to solar power *** simulations from such weather models aim to quantify uncertainty in the future development of the weather,and can be used to propagate this uncertainty through the model chain to generate probabilistic solar energy ***,ensemble prediction systems are known to exhibit systematic errors,and thus require post-processing to obtain accurate and reliable probabilistic *** overarching aim of our study is to systematically evaluate different strategies to apply post-processing in model chain approaches with a specific focus on solar energy:not applying any post-processing at all;post-processing only the irradiance predictions before the conversion;post-processing only the solar power predictions obtained from the model chain;or applying post-processing in both *** a case study based on a benchmark dataset for the Jacumba solar plant in the U.S.,we develop statistical and machine learning methods for postprocessing ensemble predictions of global horizontal irradiance(GHI)and solar power ***,we propose a neural-network-based model for direct solar power forecasting that bypasses the model *** results indicate that postprocessing substantially improves the solar power generation forecasts,in particular when post-processing is applied to the power *** machine learning methods for post-processing slightly outperform the statistical methods,and the direct forecasting approach performs comparably to the post-processing strategies.

关键词： solar forecasting post-processing probabilistic forecasting machine learning model chain