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Sequential Propagation of Chaos for Mean-Field BSDE Systems

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 11-40页

作者： Xiaochen LI kai DU Shanghai Center for Mathematical Sciences Fudan UniversityShanghai 200433China. Shanghai Artificial Intelligence Laboratory 701 Yunjin RoadShanghai 200433China

A new class of backward particle systems with sequential interaction is proposed to approximate the mean-field backward stochastic differential *** is proven that the weighted empirical measure of this particle system converges to the law of the McKean-Vlasov system as the number of particles *** on the Wasserstein met-ric,quantitative propagation of chaos results are obtained for both linear and quadratic growth ***,numerical experiments are conducted to validate our theoretical results.

关键词： Backward propagation of chaos Particle system Sequential interaction McKean-Vlasov BSDE Convergence rate

Autonomous navigation method of satellite constellation based on adaptive forgetting factors

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Chinese Journal of Aeronautics 2024年第7期37卷 317-332页

作者： Dong WANG Jing YANG kai XIONG School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Science and Technology on Space Intelligent Control Laboratory Beijing Institute of Control EngineeringBeijing 100094China

To address the problem that model uncertainty and unknown time-varying system noise hinder the filtering accuracy of the autonomous navigation system of satellite constellation,an autonomous navigation method of satellite constellation based on the Unscented Kalman Filter with Adaptive Forgetting Factors(UKF-AFF)is *** process noise covariance matrix is estimated online with the strategy that combines covariance matching and adaptive adjustment of forgetting *** adaptive adjustment coefficient based on squared Mahalanobis distance of state residual is employed to achieve online regulation of forgetting factors,equipping this method with more *** intersatellite direction vector obtained from photographic observations is introduced to determine the constellation satellite orbit together with the distance measurement to avoid rank deficiency *** that the number of available measurements varies online with intersatellite visibility in practical applications such as time-varying constellation configurations,the smooth covariance matrix of state correction determined by innovation and gain is adopted and constructed *** analysis of the proposed method is also *** effectiveness of the proposed method is verified by the Monte Carlo simulation and comparison *** estimation accuracy of constellation position and velocity of UKF-AFF is improved by 30%and 44%respectively compared to those of the extended Kalman filter,and the method proposed is also better than other several adaptive filtering methods in the presence of significant model uncertainty.

关键词： Constellation autonomous navigation Unscented Kalman filter Adaptive forgetting factor Model uncertainty Stability analysis

Study on macro and micro shear strength of continuously graded and gap-graded sand

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Particuology 2024年第3期86卷 101-116页

作者： Peiran Zhao Songyu Liu kai Wu School of Transportation Southeast UniversityNanjing210096China

The particle gradation of sand has a significant influence on its shear strength,yet the similarities and differences between the effects of continuous and gap grading have yet to be fully *** this study,the discrete element method(DEM)was used to simulate biaxial tests on granular samples that were both continuously graded and *** macroscopic analysis revealed that the shear strength of continuously graded sands increases initially and then decreases as the uniformity of particle size distribution *** the other hand,the lack of medium particles in gap-graded sands amplifies the difference in particle size between coarse and fine particles,leading to a decrease in shear ***,both continuous and gap gradings affect the internal packing structure of the particle assembly,which consequently affects particle stress distributions,contact forces,coordination numbers,stress-induced anisotropies,and contact force networks,thus having an impact on the macroscopic shear *** global uniformity of particle size distribution was unidirectionally affected by continuous grading,while gap grading had a locally bidirectional *** findings provide a better understanding of the effects of particle grading on the macroscopic shear strength of sands.

关键词： Biaxial test Shear strength Particle gradation Discrete element method Micromechanics

Robustness of the octupole collectivity in 144Ba within the cranking covariant density functional theory in 3D lattice

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Nuclear Science and Techniques 2024年第8期35卷 124-131页

作者： Ze‑kai Li Yuan‑Yuan Wang Mathematics and Physics Department North China Electric Power UniversityBeijing 102206China Hebei Key Laboratory of Physics and Energy Technology North China Electric Power UniversityBaoding 071000China

The octupole deformation and collectivity in octupole double-magic nucleus 144Ba are investigated using the Cranking covariant density functional theory in a three-dimensional lattice *** reduced B(E3)transition probability is implemented for the first time in semiclassical approximation based on the microscopically calculated electric octupole *** available data,including the I-ωrelation and electric transitional probabilities B(E2)and B(E3)are well ***,it is shown that the ground state of 144Ba exhibits axial octupole and quadrupole deformations that persist up to high spins(I≈24h).

关键词： Octupole collectivity Cranking covariant density functional theory Rotational spectrum Electric transitional probabilities

Impact of the Political Risk on Food Reserve Ratio:Evidence Across Countries

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Journal of Systems Science & Complexity 2024年第5期37卷 2071-2103页

作者： XING kai LI Shang YANG Xiaoguang School of Economics&Management Nanchang University Department of Statistics and Data Science National University of Singapore Academy of Mathematics and Systems Science Chinese Academy of Sciences University of Chinese Academy of Sciences

Using an unbalanced panel data covering 75 countries from 1991 to 2019, the authors explore how the political risk impacts on food reserve ratio. The empirical findings show that an increasing political risk negatively affects food reserve ratio, and the same effects hold for both internal risk and external risk. Moreover, the authors find that the increasing external or internal risks both negatively affect food production and food exports, but external risk does not significantly impact food imports and it positively impacts food consumption, while internal risk negatively impacts food imports and food consumption. The results suggest that most governments have difficulty raising subsequent food reserve ratios in face of an increasing political risk, no matter if it is an internal risk or an external risk although the mechanisms behind the impacts are different.

关键词： External risk food reserve ratio internal risk political risk

Corrosion behavior of Gd_(2)Zr_(2)O_(7)thermal barrier coatings under Fe-containing environmental sediment attack

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Journal of Advanced Ceramics 2024年第4期13卷 447-462页

作者： Lei Guo Yanyan Li kai Yan School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Advanced Joining Technology Key Lab of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin 300072China Key Laboratory of Special Equipment Safety and Energy-saving for State Market Regulation China Special Equipment Inspection&Research InstituteBeijing 100029China

Environmental sediments mainly consisting of CaO–MgO–Al_(2)O_(3)–SiO_(2)(CMAS)corrosion are a serious threat to thermal barrier coatings(TBCs),in which Fe element is usually ***_(2)Zr_(2)O_(7)TBCs are famous for their excellent CMAS *** this study,the characteristics of Fe-containing environmental sediments(CMAS-Fe)and their corrosiveness to Gd_(2)Zr_(2)O_(7)coatings were *** types of CMAS-Fe glass with different Fe contents were *** melting points were measured to be 1322–1344℃,and the high-temperature viscosity showed a decreasing trend with increasing Fe *** corrosion behavior of four types of CMAS-Fe to Gd_(2)Zr_(2)O_(7)coatings at 1350℃was *** the initial corrosion stage(0.1 h),anorthite was precipitated in CMAS-Fe with a high Ca:Si ratio,while Fe-garnet was formed in the melt with the highest Fe *** the corrosion time resulted in the formation of a reaction layer,which exhibited an interpenetrating network composed of Gd-oxyapatite,ZrO_(2),and residual *** spinel was precipitated within the reaction *** 1 h or even longer time,the reaction layers tended to be stable and compact,which had comparable hardness and fracture toughness to those of Gd_(2)Zr_(2)O_(7)*** the cyclic CMAS-Fe attack,the residual CMAS-Fe in the interpenetrating network provided a pathway for the redeposited CMAS-Fe infiltration,resulting in the continuous growth of the reaction *** a result,the Gd_(2)Zr_(2)O_(7)coatings had a large consumption in the thickness,degrading the coating ***,the Gd_(2)Zr_(2)O_(7)coatings exhibit unsatisfactory corrosion resistance to CMAS-Fe attack.

关键词： thermal barrier coatings(TBCs) Gd_(2)Zr_(2)O_(7) Fe-containing CaO-MgO-Al2O3-SiO_(2)(CMAS) corrosion resistance reaction layer

Model-driven full system dynamics estimation of PMSM-driven chain shell magazine

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DEFENCE TECHNOLOGY 2024年第9期39卷 147-156页

作者： Wei, kai Chen, Longmiao Zou, Quan NanJing Univ Sci & Technol Sch Mech Engn Nanjing 210094 Peoples R China

Based on the system dynamic model, a full system dynamics estimation method is proposed for a chain shell magazine driven by a permanent magnet synchronous motor (PMSM). An adaptive extended state observer (AESO) is proposed to estimate the unmeasured states and disturbance, in which the model parameters are adjusted in real time. Theoretical analysis shows that the estimation errors of the disturbances and unmeasured states converge exponentially to zero, and the parameter estimation error can be obtained from the extended state. Then, based on the extended state of the AESO, a novel parameter estimation law is designed. Due to the convergence of AESO, the novel parameter estimation law is insensitive to controllers and excitation signal. Under persistent excitation (PE) condition, the estimated parameters will converge to a compact set around the actual parameter value. Without PE signal, the estimated parameters will converge to zero for the extended state. Simulation and experimental results show that the proposed method can accurately estimate the unmeasured states and disturbance of the chain shell magazine, and the estimated parameters will converge to the actual value without strictly continuous PE signals. (c) 2024 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Chain shell magazine Full system dynamics estimation Disturbance estimation Parameter estimation Adaptive extended state observer PARAMETER-ESTIMATION NONLINEAR-SYSTEMS STATE

Nuclei-rich galvanizing strategy for suppressing zinc dendrite growth

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Rare Metals 2024年第8期43卷 4016-4018页

作者： Hai-Xia Wu kai-Lu Guo College of Chemistry and Chemical Engineering Henan Key Laboratory of Function-Oriented Porous MaterialsLuoyang Normal UniversityLuoyang 471934China

The uncontrolled growth of zinc dendrites on zinc anode hinders the application of zinc ion *** solve this problem,Lu's group proposed a nuclei-rich galvanizing strategy for suppressing the zinc dendrite *** allows the nuclei-rich zinc electrode to cycle steadily for1200 h and have a high Coulombic efficiency of 99.7%at15 mA·cm^(-2)with a deposited amount of 10 mAh·cm^(-2).Moreover,the Zn-MnO_(2) battery with a low N/P ratio of 1.9exhibited sustained cycling life.

关键词： cycling sustained battery

Beyond 1,4-addition of in-situ generated(aza-)quinone methides and indole imine methides

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Chinese Chemical Letters 2024年第7期35卷 35-53页

作者： Yan-Li Li Zhi-Ming Li kai-kai Wang Xiao-Long He Medical College Xinxiang UniversityXinxiang 453000China School of Pharmacy Xinxiang UniversityXinxiang 453000China School of Food and Bioengineering Xihua UniversityChengdu 610039China

The conjugate addition of in-situ generated(aza-)quinone methides(QMs)and indole imine methides(IIMs)emerged as a powerful protocol to access densely functionalized benzenes and *** alcohols,aminobenzhydryl alcohols,and varied indolylmethanols served as most effective precursors for the in-situ generation of such reactive species under acid *** relevant propargylic alcohol has proven to be an elegant precursor to generate the propargylic-QMs and-IIMs via the acid promoted dehydration process,thus enabling diverse challenging remote activation to proceed conjugate1,6-and 1,***,the heteroarene has proven to be workable to transfer the LUMO of the p-QMs and 2-IIMs,thus inducing the remote nucleophilic dearomative *** conjugate additions of(aza-)p-QMs and varied IIMs has made significant contribution in the field of remote activation chemistry in past *** review summarizes the latest advances of the remote conjugate additions of the in-situ generated QMs and IIMs.

关键词： Conjugate addition QMs IIMs LUMO Remote activation Dearomative addition