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Coordinating control of multiple rigid bodies based on motion primitives

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Acta Mechanica Sinica 2012年第2期28卷 482-489页

作者： Fan Wu zhi-yong Geng State Key Laboratory for Turbulence and Complex Systems Peking University100871 BeijingChina

This paper studies the problem of coordinated motion generation for a group of rigid bodies. Two classes of coordinated motion primitives, relative equilibria and ma- neuvers, are given as building blocks for generating coordi- nated motions. In a motion-primitive based planning frame- work, a control method is proposed for the robust execution of a coordinated motion plan in the presence of perturba- tions. The control method combines the relative equilibria stabilization with maneuver design, and results in a close- loop motion planning framework. The performance of the control method has been illustrated through a numerical sim- ulation.

关键词： Coordinating control Motion plan execution Motion primitive. Relative equilibrium. Maneuver

Stabilization of coordinated motion for underwater vehicles

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Acta Mechanica Sinica 2011年第3期27卷 438-444页

作者： Fan Wu zhi-yong Geng State Key Laboratory for Turbulence and Complex Systems Peking University 100871 Beijing China

This paper presents a coordinating and stabilizing control law for a group of underwater vehicles with unstable dynamics. The coordinating law is derived from a potential that only depends on the relative configuration of the underwater vehicles. Being coordinated,the group behaves like one mechanical system with symmetry,and we focus on stabilizing a family of coordinated motions,called relative equilibria. The stabilizing law is derived using energy shaping to stabilize the relative equilibria which involve each vehicle translating along its longest（unstable） axis without spinning,while maintaining a relative configuration within the group. The proposed control law is physically motivated and avoids the linearization or cancellation of nonlinearities.

关键词： Underwater vehicles . Coordination .Relativeequilibria. Stabilization. Energy shaping

Numerical study on the dynamic fracture of explosively driven cylindrical shells

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Defence Technology（防务技术） 2023年第9期27卷 154-168页

作者： zhi-yong Yin Xiao-wei Chen State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China School of Mechatronical Engineering Beijing Institute of TechnologyBeijing100081China Advanced Research Institute of Multidisciplinary Sciences Beijing Institute of TechnologyBeijing100081China

Research on the expansion and fracture of explosively driven metal shells has been a key issue in weapon development and structural *** is important to study and predict the failure mode,fracture mechanism,and fragment distribution characteristics of explosively driven metal *** this study,we used the finite element-smoothed particle hydrodynamics(FE-SPH)adaptive method and the fluid-structure interaction method to perform a three-dimensional numerical simulation of the expansion and fracture of a metal cylindrical *** method combined the advantages of the FEM and SPH,avoiding system mass loss,energy loss,and element distortion;in addition,the proposed method had a good simulation effect on the interaction between detonation waves and the cylindrical *** simulated detonation wave propagation,shell damage morphology,and fragment velocity distribution were in good agreement with theoretical and experimental *** divided the fragments into three regions based on their shape *** analyzed the failure mode and formation process of fragments in different *** numerical results reproduced the phenomenon in which cracks initiated from the inner surface and extended to the outer surface of the cylindrical shell along the 45°or 135°shear *** addition,fragments composed of elements are identified,and the mass and characteristic lengths of typical fragments at a stable time are ***,the mass and size distribution characteristics of the fragments were explored,and the variation in the fitting results of the classical distribution function under different explosion pressures was ***,based on mathematical derivation,the distribution formula of fragment velocity was *** improved formula provided higher accuracy and could be used to analyze any metal cylindrical shells with different length-to-diameter ratios.

关键词： Metal cylindrical shell Shear failure Fragment distribution Numerical simulation Fragment velocity

Investigations on Left Hand Cut Contribution to Determination of κ（700） Pole

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Communications in Theoretical Physics 2007年第5期47卷 883-886页

作者： ZHOU zhi-yong Department of Physics Peking University Beijing 100871 China

The uncertainties of background contributions to J = 0 partial wave πK scattering phase shifts are carefully studied. We firstly point out that the circular cuts exhibit different characters in S1/1 and S3/2 waves. While the former contributes negatively to the scattering length parameter, the latter contributes positively, i.e., has a wrong sign. This fact indicates that short range force contribu tions to the phase shift are non-negligible in the exotic channel. Nevertheless, it is verified that the κ pole will be affected only slightly with respect to the theoretical uncertainty in estimating the left hand cut contributions.

关键词： πK scattering unitarity dispersion relations κ resonance

Intensity distribution function and statistical properties of fast radio bursts

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Research in Astronomy and Astrophysics 2017年第1期17卷 71-80页

作者： Long-Biao Li yong-Feng huang zhi-Bin Zhang Di Li Bing Li School of Astronomy and Space Science Nanjing University Nanjing 210046 China Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education Nanjing210046 China Department of Physics College of Sciences Guizhou University Guiyang 550025 China National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Key Laboratory for Radio Astronomy Chinese Academy of Sciences Nanjing 210008 China Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

Fast Radio Bursts （FRBs） are intense radio flashes from the sky that are characterized by mil- lisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discovered. Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be ~ 660 pc cm-3, supporting their being from a cosmological origin. Their energy released in the radio band spans about two orders of magnitude, with a mean value of ~ 10-39 erg. More interestingly, although the study of FRBs is still in a very early phase, the published collection of FRBs enables us to derive a useful intensity distribution function. For the 16 non-repeating FRBs detected by the Parkes telescope and the Green Bank Telescope, the intensity distribution can be described as dN/dFobs = （4.1± 1.3） × 103 F-obs1.1±0.2 sky-1 d-l, where Fobs is the observed radio obs fluence in units of Jy ms. Here the power-law index is significantly flatter than the expected value of 2.5 for standard candles distributed homogeneously in a flat Euclidean space. Based on this intensity distribution function, the Five-hundred-meter Aperture Spherical radio Telescope （FAST） is predicted to be able to detect about five FRBs for every 1000 h of observation time.

关键词： pulsars general - stars neutron - radio continuum general - intergalactic medium -methods statistical

Curvature Estimates of Hypersurfaces in the Minkowski Space

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Chinese Annals of Mathematics,Series B 2013年第5期34卷 753-764页

作者： yong huang Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences

A class of curvature estimates of spacelike admissible hypersurfaces related to translating solitons of the higher order mean curvature flow in the Minkowski space is ob- tained, which may offer an idea to study an op... 详细信息

关键词： Minkowski space Hypersurface Curvature estimates Translating solitons

SiS_(2)/ZnO范德华异质结光催化水分解第一性原理研究

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原子与分子物理学报 2025年第6期42卷 31-36页

作者：李家豪黄欣杨志红南京邮电大学电子与光学工程学院、柔性电子(未来技术)学院南京210023 南京邮电大学理学院南京210023

基于第一性原理方法,研究了SiS_(2)/ZnO范德华异质结的电子结构和光催化性质.结果表明,SiS_(2)/ZnO异质结是带隙值为1.32 eV的半导体材料,表现出交错排列的能带结构.在异质结界面处,形成了从ZnO指向SiS_(2)的内置电场,该内置电场的存在... 详细信息

基于第一性原理方法,研究了SiS_(2)/ZnO范德华异质结的电子结构和光催化性质.结果表明,SiS_(2)/ZnO异质结是带隙值为1.32 eV的半导体材料,表现出交错排列的能带结构.在异质结界面处,形成了从ZnO指向SiS_(2)的内置电场,该内置电场的存在使得SiS_(2)/ZnO异质结中形成了特殊的“Z-型”载流子迁移模式,有利于电子空穴对的有效分离,同时增强了载流子的氧化还原能力.异质结构具有良好的热力学稳定性,且带边位置跨越水的氧化还原电位.与单层材料相比,SiS_(2)/ZnO异质结光吸收谱出现红移现象,表现出更宽的光吸收范围(从可见光到紫外光)及更强的光吸收强度(达到10~5 cm^(-1)量级).另外,通过施加双轴应变,可以有效调控SiS_(2)/ZnO异质结的带隙值.以上结果表明SiS_(2)/ZnO异质结有潜力成为新型光催化剂用于全解水.

关键词： SiS_(2)/ZnO Z-型范德华异质结光催化电子结构第一性原理

Perylene Diimide Based Isomeric Conjugated Polymers as Efficient Electron Acceptors for All-polymer Solar Cells

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Chinese Journal of Polymer Science 2019年第1期37卷 18-27,1-5页

作者： Xiao-Cheng Liu Qing-Wu Yin zhi-Cheng Hu Zhen-Feng Wang Fei huang yong Cao State Key Laboratory of Luminescent Materials and Devices School of Materials Science and Engineering South China University of Technology South China Institute of Collaborative Innovation

We present here a series of perylene diimide(PDI)based isomeric conjugated polymers for the application as efficient electron acceptors in all-polymer solar cells(all-PSCs).By copolymerizing PDI monomers with 1,4-diethynylbenzene(para-linkage)and 1,3-diethynylbenzene(meta-linkage),isomeric PDI based conjugated polymers with parallel and non-parallel PDI units inside backbones were *** was found that para-linked conjugated polymer(PA)showed better solubility,strongerπ-πstacking,more favorable blend morphology,and better photovoltaic performance than those of meta-linked conjugated polymers(PM)*** based on PTB7-Th:PA(PTB7-Th:poly{4,8-bis[5-(2-ethylhexyl)-thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophene-4,6-diyl})showed significantly enhanced photovoltaic performance than that of PTB7-Th:MA(3.29%versus 0.92%).Moreover,the photovoltaic performance of these polymeric acceptors could be further improved via a terpolymeric *** copolymerizing a small amount of meta-linkages into PA,the optimized terpolymeric acceptors enabled to enhance photovoltaic performance with improved the short-circuit current density(Jsc)and fill factor(FF),resulting in an improved power conversion efficiency(PCE)of 4.03%.

关键词： Isomeric conjugated polymers All-polymer solar cells Electron acceptors Perylene diimide

Dynamics evolution of γ' precipitates size and composition interface between γ/γ' phases in Ni-Al alloy at different aging temperatures

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Rare Metals 2022年第10期41卷 3552-3559页

作者： Xing-Chao Wu yong-Sheng Li Wei Liu zhi-Yuan Hou Meng-Qiong huang School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing210094China

The precipitation dynamics of γ’(L1-NiAl)phase and composition interfacial width between γ(fcc Ni)and γ’ phase were investigated using the phase field simulation linking with CALPHAD *** coarsening rate and particle size distribution(PSD) of γ’ phase,the temporal composition interfacial width of γ/γ’ in Ni-17 at% Al alloy aged at 923,973 and 1023 K were *** the aging temperature increases,the morphology of γ’ phase changes from the interconnected rectangle shape to the separated cuboidal *** average particle radius() of γ’ phase at coarsening stage follows ∞t^(n) with the exponents n=0.21,0.23 and 0.26,*** peak values of simulated PSDs at 923 K are less than the value calculated by the Lifshitz-Slyozov-Wagner(LSW) model,and the width of simulated PSD increases at later stage of *** normalized radius(r/)which corresponds to the peak value of PSD moves from1.1 to 1.0 as the aging temperature increases from 923 to1023 K,and they are smaller than that of LSW *** composition interfacial width decreases as the aging progresses and increases as the aging temperature increases.

关键词： Ni-Al alloy Precipitation Dynamics Particle size distribution Composition interface Phase field