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Several equivalent characterizations of fractional Hajlasz-Morrey-Sobolev spaces

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Applied Mathematics(A Journal of Chinese Universities) 2016年第3期31卷 343-354页

作者： yuAN Wen lu yu-feng YANG Da-chun School of Mathematical Sciences Beijing Normal University Laboratory of Mathematics and Complex Systems Ministry of Education Beijing 100875 China.

In this article, the authors establish several equivalent characterizations of fractional Hajlasz-Morrey-Sobolev spaces on spaces of homogeneous type in the sense of Coifman and Weiss.

关键词： Sobolev space Morrey space Morrey-Sobolev space Haj lasz gradient space of homogeneous type maximal operator

Little Hankel Operators on the Weighted Bergman Space of the Unit Ball

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Communications in Mathematical Research 2010年第4期26卷 304-312页

作者： ZHANG KAN lu yu-feng LIU CHAO-MEI School of Mathematical Sciences Dalian University of TechnologyDalian116024 College of Sciences Shenyang Agricultural UniversityShenyang110866 School of Science Dalian Jiaotong UniversityDalian116028

In this paper we mainly consider little Hankel operators with squareintegrable symbols on the weighted Bergman spaces of the unit ball.We obtain that Schatten class of little Hankel operators is equivalent to Schatten class of positive Toeplitz operators under the conditions that SMO（f） ∈ L p/2 （B n,dλ） and 2 ≤ p ∞,which is very important to research the relation between Toeplitz operators and little Hankel operators.

关键词： weighted Bergman space little Hankel operator unit ball

通过实验探究促进学生自主建构概念模型——配合物

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化学教育（中英文） 2024年第7期45卷 50-55页

作者：朱成东谷慧心鹿钰锋徐泓孙影安徽省教育科学研究院安徽合肥230061 安徽师范大学化学与材料科学学院安徽芜湖241002 合肥工业大学附属中学安徽合肥230009 安徽省宣城市教体局教研室安徽宣城242000

以[Co(NH_(3))_(5)Cl]Cl_(2)在水溶液中如何电离为问题情境,借助手持传感器展开定性以及定量实验探究活动,结合实验证据引发对三价钴离子微观结构的探讨,从而自主构建配合物的相关概念。再通过创设实验情境,如:“向硫酸铜溶液中逐滴滴... 详细信息

以[Co(NH_(3))_(5)Cl]Cl_(2)在水溶液中如何电离为问题情境,借助手持传感器展开定性以及定量实验探究活动,结合实验证据引发对三价钴离子微观结构的探讨,从而自主构建配合物的相关概念。再通过创设实验情境,如:“向硫酸铜溶液中逐滴滴加浓氨水至过量生成四氨合铜离子”“[Co(NH_(3))_(4)Cl_(2)]Cl呈现紫色和绿色2种颜色”等,激发学生展开联想质疑、模型搭建的课堂活动,促进学生学习方式转变,强化“结构决定性质”的化学观念。

关键词：实验探究实验情境配合物模型建构

Capturing and visualizing the phase transition mediated thermal stress of thermal barrier coating materials via a cross-scale integrated computational approach

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Journal of Advanced Ceramics 2024年第4期13卷 413-428页

作者： Mengdi Gan Tianlong lu Wei yu Jing feng Xiaoyu Chong Faculty of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China

The generation and evaluation of severely high thermal stress(σ)is known to be responsible for failure of thermal barrier coatings(TBCs)during thermal cycling.It is crucial and challenging to capture fluctuations inσcaused by the phase transition,which has motivated us to develop a high-throughput multiscale evaluation method forσin TBCs that considers the phase transition of the top ceramic materials by coupling first-principles calculations with finite element simulations.The method quantitatively evaluates and visualizesσof the real TBC structure under thermal cycling by multifield coupling.Additionally,the thermophysical properties calculated by the first-principles calculations consider the effects of temperature and phase transition,which not only reduces the cost of obtaining data but also has a more physical connotation.In this work,rare earth tantalites(RETaO4)are introduced as ceramic layers,and the results demonstrate thatσundergoes a rapid escalation near the phase transition temperature(Tt),particularly in the TBCs_GdTaO4 system,where it rises from 224 to 435 MPa.This discontinuity inσmay originate from the significant alterations in Young’s modulus(increase by 27%–78%)and thermal conductivity(increase by 53%–146%)near Tt.The TBCs_NdTaO4 and TBCs_SmTaO4 systems exhibit noteworthy temperature drop gradients and minimalσfluctuations,which are beneficial for extending service lifetime of TBCs.This approach facilitates the prediction of failure mechanisms and provides theoretical guidance for the reverse design of TBC materials to obtain low thermal stress systems.

关键词： thermal conductivity first-principles calculations thermodynamics thermal stress thermophysical properties

Stage separation of recoverable liquid launch vehicle by using moving pulsating ball analogue for propellant sloshing

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Chinese Journal of Aeronautics 2024年第2期37卷 360-370页

作者： yu lu Baozeng yuE Bailong HAO Bole MA feng LIU yuanyuan CHANG School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Beijing Institute of Astronautical Systems Engineering Beijing 100076China

In the process of stage separation of recoverable liquid launch vehicles,because of the large amount of residual fuel in the storage tanks,the influence of liquid sloshing on separation safety must be considered.Considering calculation simplicity and operation practicability,the Moving Pulsating Ball Model(MPBM)of large amplitude liquid sloshing is introduced into the calculation of launch vehicle stage separation.Combining the dynamic equation of the model with the energy relationship during"breathing movement",the formula calculating the force of liquid on the rigid body is derived.Compared with the calculations of commercial CFD calculation software,the accuracy of MPBM model is verified.Then,all the external forces and moments are applied to the rigid body of the stages,so that the translational and rotational dynamic equations of the stages are obtained respectively.According to the relative position of the two stages,the geometric shape of the interstage section and the engine of the second stage,the minimum clearance in the separation process can be decided to guarantee that the separation process is safe.

关键词： Moving Pulsating Ball Model(MPBM) Dynamics of stage separation Large amplitude sloshing Recoverable liquid launch vehicle Flight dynamics

Reducing Subspaces of Toeplitz Operators Induced by a Class of Non-analytic Monomials over the Unit Ball

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Acta Mathematica Sinica,English Series 2024年第7期40卷 1767-1777页

作者： Yan yue SHI Bo ZHANG Xu TANG yu feng lu School of Mathematical Sciences Ocean University of China School of Mathematics and Information Sciences Yantai University School of Mathematical Sciences Space Engineering University School of Mathematical Sciences Dalian University of Technology

In this paper, we describe the minimal reducing subspaces of Toeplitz operators induced by non-analytic monomials on the weighted Bergman spaces and Dirichlet spaces over the unit ball B2. It is proved that each minimal reducing subspace M is finite dimensional, and if dim M ≥ 3,then M is induced by a monomial. Furthermore, the structure of commutant algebra ■ is determined by N and the two dimensional minimal reducing subspaces of ■. We also give some interesting examples.

关键词： Reducing subspace operator-weighted shifts Toeplitz operator von Neumann algebra 47B35 47B37

Metabolites isolated from Penicillium HDS-Z-1E, an endophytic fungal strain isolated from Taxus cuspidata and their activation effect of catalase

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Chinese Herbal Medicines 2024年第2期16卷 227-230页

作者： Chuan Tang Rui Gao Xiaoyuan Tang yu Zhang Weixing feng Baomin feng Xuan lu College of Life and Health Dalian UniversityDalian 116622China

Objective:To study the compounds isolated from Penicillium HDS-Z-1E,an endophytic fungal strain isolated from Taxus cuspidata and their activation effect of catalase(CAT).Methods:The chemical constituents were isolated from Penicillium HDS-Z-1E,by using silica gel,Sephadex LH-20 and HPLC.The structural elucidations of five metabolites were elucidated on the basis of spectroscopic including 1 H-NMR,13C-NMR,HMBC and HSQC.Their activation sites of catalase have been investigated by molecular docking.Results:Five metabolites,compounds(1–5)were isolated from Penicillium HDS-Z-1E and identified as 4-hydroxy-4-methyltetrahydro-2H-pyran-2-one(1),4-hydroxymethyl-5,6-dihydro-pyran-2-one(2),5,6-dihydro-2-oxo-2H-pyran-4-carboxylic(3),N-acetyl-hydrazinobenzoic acid(4),and methyl 2-(2,5-dihydroxyphenyl)acetate(5).Conclusion:Compound 3 is a new compound.Compounds 3 and 4 may have potential activators of catalase,providing a theoretical basis for the development of CAT activators.

关键词： catalase activators 5,6-dihydro-2-oxo-2H-pyran-4-carboxylic molecular simulation penicillium Taxus cuspidata Sieb.et Zucc

STGNN-LMR:A Spatial–Temporal Graph Neural Network Approach Based on sEMG Lower Limb Motion Recognition

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Journal of Bionic Engineering 2024年第1期21卷 256-269页

作者： Weifan Mao Bin Ma Zhao Li Jianxing Zhang Yizhou lu Zhuting yu feng Zhang Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201210China University of Chinese Academy of Sciences Beijing 101408China University of Science and Technology of China Hefei 230026China Shanghai Zhongyan Jiuyi Technology Co. Ltd.Shanghai 201821China Academy of Military Science Bejing 100091China

Lower limb motion recognition techniques commonly employ Surface Electromyographic Signal(sEMG)as input and apply a machine learning classifier or Back Propagation Neural Network(BPNN)for classification.However,this artificial feature engineering technique is not generalizable to similar tasks and is heavily reliant on the researcher’s subject expertise.In contrast,neural networks such as Convolutional Neural Network(CNN)and Long Short-term Memory Neural Network(LSTM)can automatically extract features,providing a more generalized and adaptable approach to lower limb motion recognition.Although this approach overcomes the limitations of human feature engineering,it may ignore the potential correlation among the sEMG channels.This paper proposes a spatial–temporal graph neural network model,STGNN-LMR,designed to address the problem of recognizing lower limb motion from multi-channel sEMG.STGNN-LMR transforms multi-channel sEMG into a graph structure and uses graph learning to model spatial–temporal features.An 8-channel sEMG dataset is constructed for the experimental stage,and the results show that the STGNN-LMR model achieves a recognition accuracy of 99.71%.Moreover,this paper simulates two unexpected scenarios,including sEMG sensors affected by sweat noise and sudden failure,and evaluates the testing results using hypothesis testing.According to the experimental results,the STGNN-LMR model exhibits a significant advantage over the control models in noise scenarios and failure scenarios.These experimental results confirm the effectiveness of the STGNN-LMR model for addressing the challenges associated with sEMG-based lower limb motion recognition in practical scenarios.

关键词： Lower limb motion recognition Exoskeleton sEMG.Graph neural network Noise Sensor failure

Constructing S-scheme charge separation in cobalt phthalocyanine/oxygen-doped g-C_(3)N_(4) heterojunction with enhanced photothermal-assisted photocatalytic H_(2) evolution

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Rare Metals 2024年第1期43卷 198-211页

作者： Wei-Long Shi Zheng Xu yu-Xing Shi Ling-Ling Li Jia-Lin lu Xin-Hai Sun Xin Du feng Guo Chang-yu lu School of Material Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China School of Energy and Power Jiangsu University of Science and TechnologyZhenjiang 212003JiangsuChina College of Chemistry Zhengzhou UniversityZhengzhou 450001China School of Water Resource and Environment Hebei Province Key Laboratory of Sustained Utilization and Development of Water RecourseHebei Center for Ecological and Environmental Geology ResearchHebei Geo UniversityShijiazhuang 050031China

Hydrogen acquisition from solar energy is an effective way to address energy crisis,which makes the development of efficient photocatalysts become the main direction of scientific research.Herein,cobalt phthalocyanine/oxygen-doped g-C_(3)N_(4)(CoPc/OCN) S-scheme heterojunction photocatalyst was designed by coupling multi-step calcination with solvothermal method for enhanced photothermal-assisted photocatalytic H_(2) evolution.The multistep calcined g-C_(3)N_(4) is easier for O-doping formation,and the ethanol solvothermal strategy is utilized to enhance the dispersion of CoPc on OCN nano sheet surface and forms sufficient S-scheme heterojunction through H-bonds.In addition,the active sites and excellent photothermal properties of CoPc itself further improve the integrated photocatalytic activity of CoPc/OCN S-scheme heterojunction.The optimal photocatalytic hydrogen evolution rate of CoPc/OCN S-scheme heterojunction photocatalyst reached 9.56 mmol·g^(-1)·h^(-1),which is 2.69 and 1.23 times higher than that of CN and OCN,respectively.This work provides a valuable design idea and scheme for enhancing the multi-factor co-assisted photocatalytic H_(2) evolution performance.

关键词： Photothermal Photocatalytic H_(2)evolution Cobalt phthalocyanine Oxygen-doped g-C_(3)N_(4) Sscheme heterojunction