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Decay properties of the X(3872)through the Fierz rearrangement

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Communications in Theoretical Physics 2022年第2期74卷 60-77页

作者： hua-Xing chen School of Physics Southeast UniversityNanjing 210094China

We systematically construct all the tetraquark currents of J^(PC)=1^(++) with the quark configurations[cq][cq],[cq][qc],and[cc][qq](q=u/d).Their relations are derived using the Fierz rearrangement of the Dirac and color indices,through which we study decay properties of the X(3872)under both the compact tetraquark and hadronic molecule *** conduct a search for the X(3872)→χ_(c0)π,η_(c)ππ,and χ_(c1)ππ decay processes in particle experiments.

关键词： exotic hadron tetraquark state hadronic molecule Fierz rearrangement QCD sum rules

Dynamic Behavior Analysis of Finger Seal Based on Equivalent Dynamic Model

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Chinese Journal of Mechanical Engineering 2010年第5期23卷 590-599页

作者： SU hua chen Guoding School of Mechatronics Northwestern Polytechnical University Xi ＇an 710072 China

Finger seal is a new technology developed for gas path sealing in gas turbine *** has been paid attention to its good sealing performance and lower manufacture *** vibration behavior of finger seal is not be considered in performance analysis for the contact finger seal with compliant geometric configuration,then this will influence the reliability of the performance analysis and the parametric design of a finger *** to the dynamic character of finger seal,the harmonic vibration and free vibration models of a repetitive section of a two-layer finger seal that contains one high and one low finger seal are established *** dynamic behavior of finger seal in different working conditions is obtained based on the dynamic response analysis of finger＇s *** dynamic low hysteresis and low wear terms based on the equivalent dynamic model of finger seal are put forward,which can be used to predict the dynamic behavior of finger *** an example,the dynamic behaviors of an 8-layer finger seal and a 10-layer finger seal were predicted,and the validity of the prediction was demonstrated by the leakage test results of these two finger *** work presented here not only could make the dynamic analysis of finger seal with complicated structure simple and easy especially for multi-layer finger seal system,but also suggest a useful method for designing the finger seal with good dynamic behavior by means of different seal layers assembly.

关键词： finger seal dynamic behavior vibration

Optimal Design of Stewart Platform Safety Mechanism

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Chinese Journal of Aeronautics 2007年第4期20卷 370-377页

作者： chen hua chen Weishan Liu Junkao School of Mechatronics Engineering Harbin Institute of Technology Harbin 150001 China

A safety mechanism capable of moving at will within the range of its whole link lengths is designed based on the link space. Sixteen extreme poses are obtained in a Stewart platform. The singular points of the extreme poses are solved by using homotopy method as well as the judgment condition of singular points, and thereby the maximum link lengths are achieved. The rotation angles of joints and the distances between two neighboring links are analyzed in a calculation example in which that the mechanism moves among the extreme poses is assumed. Then an algorithm to test the safety mechanism is presented taking the constraint conditions into account. A safety mechanism having optimal properties of global movement is worked out by optimizing all structural parameters through minimizing the average condition number of extreme poses.

关键词： parallel manipulator safety mechanism optimal design Stewart platform

Neottia wuyishanensis(Orchidaceae:Neottieae),a new species from Fujian,China

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Plant Diversity 2021年第5期43卷 426-431页

作者： Bing-hua chen Xiao-hua Jin College of Life Sciences Fujian Normal UniversityFuzhou 350117China State Key Laboratory of Systematic and Evolutionary Botany and Herbarium Institute of BotanyChinese Academy of SciencesBeijing 100093China The Public Service Platform for Industrialization Development Technology of Marine Biological Medicine and Products of the State Oceanic Administration Fujian Key Laboratory of Special Marine Bioresource Sustainable UtilizationSouthern Institute of OceanographyCollege of Life SciencesFujian Normal UniversityFuzhou 350117China

A new species,Neottia wuyishanensis(Neottieae,Orchidaceae),is described and illustrated from Wuyishan,Fujian,eastern China,based on morphological characters and molecular *** phylogenetics indicate that *** is nested within the clade formed by Neottia fugongensis and Neottia ***,*** is similar to *** and ***,but differs from them by having indistinct auricles at the base,and in the shape and size of lobelets.

关键词： China Neottia wuyishanensis New species Orchidaceae

Hierarchically porous materials and green carbon science——an interview with Ming-Yuan He

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National Science Review 2020年第11期7卷 1759-1761页

作者： Li-hua chen Wuhan University of Technology

Many examples of hierarchies are present in nature, such as water transport in leaf vein systems, the respiratory system, the blood circulatory system, etc. Hierarchically structuring a material over different length scales by mimicking natural systems can provide an opportunity to render the material suitable for a variety of functions.

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Development of nonlinear disturbance observer based control and nonlinear PID： A personal note

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Control Theory and Technology 2018年第4期16卷 284-300页

作者： Wen-hua chen Department of Aeronautical and Automotive Engineering Loughborough University Loughborough Leicestershire LE11 3TU U.K.

This paper gives an overview of early development of nonlinear disturbance observer design technique and the disturbance observer based control （DOBC） design. Some critical points raised in the development of the methods have been reviewed and discussed which are still relevant for many researchers or practitioners who are interested in this method. The review is followed by the development of a new type of nonlinear PID controller for a robotic manipulator and its experimental tests. It is shown that, under a number of assumptions, the DOBC consisting of a predictive control method and a nonlinear disturbance observer could reduce to a nonlinear PID with special features. Experimental results show that, compared with the predictive control method, the developed controller significantly improves performance robustness against uncertainty and friction. This paper may trigger further research and interests in the development of DOBC and related methods, and building up more understanding between this group of control methods with comparable ones （particularly control methods with integral action）.

关键词： Disturbance observer nonlinear control PID controller disturbance observer based contro

Existence of the Eigenvalues for the Cone Degenerate p-Laplacian

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Chinese Annals of Mathematics,Series B 2021年第2期42卷 217-236页

作者： hua chen Yawei WEI School of Mathematics and Statistics Wuhan UniversityWuhan 430072China School of Mathematical Sciences and LPMC Nankai UniversityTianjin 300071China

The present paper is concerned with the eigenvalue problem for cone degenerate p-Laplacian. First the authors introduce the corresponding weighted Sobolev spaces with important inequalities and embedding properties. Then by adapting LusternikSchnirelman theory, they prove the existence of infinity many eigenvalues and eigenfunctions. Finally, the asymptotic behavior of the eigenvalues is given.

关键词： Quasi-linear Degenerate operator Variational methods

The effect of agglomerate on micro-structural evolution in solid-state sintering

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Acta Mechanica Sinica 2012年第5期28卷 1323-1330页

作者： Chao Wang Shao-hua chen State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences

Discrete element method （DEM） is used in the present paper to simulate the microstructural evolution of a planar layer of copper particles during sintering. Formation of agglomerates and the effect of their rearrangement on densification are mainly focused on. Comparing to the existing experimental observations, we find that agglomerate can form spontaneously in sintering and its rearrangement could accelerate the densification of compacts. Snapshots of numerical simulations agree qualitatively well with experimental observations. The method could be readily extended to investigate the effect of agglomerate on sintering in a three- dimensional model, which should be very useful for understanding the evolution of microstructure of sintering systems.

关键词： Solid-state sintering Discrete element method Agglomerate Densification Micro-structural evolution

Factors influencing particle agglomeration during solid-state sintering

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Acta Mechanica Sinica 2012年第3期28卷 711-719页

作者： Chao Wang Shao-hua chen State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences100190 BeijingChina

Discrete element method （DEM） is used to study the factors affecting agglomeration in three-dimensional copper particle systems during solid-state sintering. A new parameter is proposed to characterize agglomeration. The effects of a series of factors are studied, including particle size, size distribution, inter-particle tangential viscosity, tem- perature, initial density and initial distribution of particles on agglomeration. We find that the systems with smaller particles, broader particle size distribution, smaller viscos- ity, higher sintering temperature and smaller initial density have stronger particle agglomeration and different distribu- tions of particles induce different agglomerations. This study should be very useful for understanding the phenomenon of agglomeration and the micro-structural evolution during sin- tering and guiding sintering routes to avoid detrimental ag- glomeration.

关键词： Solid-state sintering Discrete element simula-tion. Agglomeration. Densification