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Design optimization of a hexapod vibration isolation system for electro-optical payload

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Chinese Journal of Aeronautics 2024年第2期37卷 330-342页

作者： Jing li.Weipeng li.Xiaoyan ZHANG hai HUANG School of Astronautics Beihang UniversityBeijing 100191China

The electro-optical payloads on mobile platforms generally suffer undesirable vibrations generated by maneuvers and *** vibrations are in six degrees of freedom and cause li.e-of-sight jitters,resulting in image blurring and loss of tracking *** this paper,a Hexapod Vibration Isolation System(HVIS)is proposed and optimized to solve this *** optimization aims to centrali.e and minimize the natural frequencies of HVIS,for expanding the vibration isolation bandwidth and improving the vibration isolation in the higher frequency *** that the design space for HVIS is li.ited and interfered with the frames of the mobile platform,a non-colli.ion algorithm is proposed and appli.d in the optimization to obtain the feasible optimal *** optimization result shows that the natural frequency bandwidth has been reduced by 42.9%,and the maximum natural frequency is reduced by 30.2%.The prototypes of initial and optimal designs are manufactured and *** simulated and experimental results demonstrate the vali.ity of the optimization,and the optimal design provides a maximum of 15 dB more isolation in rotation direction than the initial design.

关键词： Electro-optical payload Vibrations Isolation system Hexapod Optimization Non-colli.ion design

Layered niobium carbide enabli.g excellent kinetics and cycli.g stabili.y of li.Mg-B-H hydrogen storage material Layered niobium carbide enabli.g excellent kinetics

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Rare Metals 2024年第3期43卷 1153-1166页

作者： li.Wen Lu Hui Luo Guang-Xu li.Yun li.Xin-Hua Wang Cun-Ke Huang Zhi-QiangLan Wen-Zheng Zhou Jin Guo Mohammad Ismail hai-Zhen li. Guangxi Novel Battery Materials Research Center of Engineering Technology Guangxi Colleges and Universities Key Laboratory of Blue Energy and Systems IntegrationSchool of Physical Science and TechnologyGuangxi UniversityNanning530004China State Key Laboratory of Featured Metal Materials and li.e-Cycle Safety for Composite Structures Nanning530004China School of Mechanical and Electrical Engineering Quzhou College of TechnologyQuzhou324000China Department of Materials Science and Engineering Zhejiang UniversityHangzhou310027China Faculty of Ocean Engineering Technology and Informatics Universiti Malaysia Terengganu21030Kuala NerusTerengganuMalaysia Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Nankai UniversityTianjin300071China

The li.Mg-B-H composite(2li.H_(4)+MgH_(2))has a high capacity of 11.4 wt%as a hydrogen storage ***,the slow kinetics and poor cycli.g stabili.y severely restrict its practical *** this work,a layered Nb_(2)C MXene was first synthesized and then introduced to tailor the kinetics and cycli.g stabili.y of the li.Mg-B-H *** milled 2li.+MgB_(2)composites were initially hydrogenated to obtain the 2li.H_(4)+MgH_(2)*** 2li.H_(4)+MgH_(2)+5wt%Nb_(2)C can release 9.0 wt%H_(2)in 30 min at 400℃,while it is only 2.7 wt%for the undoped 2li.H_(4)+MgH_(2).The dehydrogenation activation energies of MgH_(2)and li.H_(4)are 123 and 154 kJ·mol^(-1)respectively for the 5 wt%Nb_(2)C-doped composite,lower than the undoped composite(164 and 165 kJ·mol^(-1)).The 2li.H_(4)+MgH_(2)+5 wt%Nb_(2)C possesses excellent cycli.g stabili.y,with the reversible capacity only sli.htly reduced from 9.4 wt%for the 1st cycle to 9.3 wt%for the 20th ***_(2)C keeps stable in the composite and acts as an efficient catalyst for the li.Mg-B-H *** is beli.ved that both the layered structure and the active Nb element contribu te to the enhanced hydrogen storage performances of the li.Mg-B-H *** work confirms that the Nb_(2)C MXene with layered stru cture has a significant enhancing impact on the li.Mg-B-H hydrogen storage materials,which is different from the bulk NbC.

关键词： Hydrogen storage li.hium borohydride Magnesium hydride Nb_(2)C MXene

Global existence and large-time behavior for primitive equations with the free boundary

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Science China Mathematics 2024年第10期67卷 2303-2330页

作者： hai-li.ng li.Chuangchuang li.ng School of Mathematical Sciences Capital Normal UniversityBeijing 100048China Academy for Multidiscipli.ary Studies Capital Normal UniversityBeijing 100048China College of Mathematics and Statistics Chongqing UniversityChongqing 401331China

In the present paper, the primitive equations, which can be used to simulate the large-scale motion of the ocean and atmosphere, are considered in the three-dimensional domain bounded below by a fixed soli. boundary and above by a free-moving boundary. The global existence and uniqueness of strong solutions are establi.hed, and the long-time convergence to the equili.rium state is shown to be either at an exponential rate for the horizontal periodic domain or at an algebraic rate for the horizontal whole space.

关键词： primitive equations the free boundary value problem global well-posedness large-time behavior

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Fatigue-resistant Hydrogels

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Chemical Research in Chinese Universities 2024年第1期40卷 64-77页

作者： li.Luofei LEI hai CAO Yi Collaborative Innovation Center of Advanced Microstructures National Laboratory of Solid State MicrostructureDepartment of PhysicsNanjing UniversityNanjing 210093P.R.China Department of Physics Zhejiang UniversityHangzhou 310027P.R.China

Hydrogels have been extensively studied for appli.ations in various fields, such as tissue engineering and soft robotics, as determined by their mechanical properties. The mechanical design of hydrogels typically focuses on the modulus, toughness, and deformabili.y. These characteristics play important roles and make great achievements for hydrogel use. In recent years, a growing body of research has concentrated on the fatigue property of hydrogels, which determines their resistance to crack propagation in the networks during cycli. mechanical loads for appli.ations. However, knowledge of hydrogel fatigue behavior remains notably deficient. Here, we present a brief overview of the fatigue behavior of hydrogels, encompassing the general experimental methods to measure the fatigue property and fundamental theoretical calculation models. Then, we highli.ht multiple strategies to enhance the fatigue resistance of hydrogels. Finally, we present our perspectives on fatigue-resistant hydrogels, outstanding challenges and potential directions for future research.

关键词： Hydrogel Fatigue-resistant Fracture

li.hium-induced graphene layer containing li.(3)P alloy phase to achieve ultra-stable electrode interface for li.hium metal anode

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Rare Metals 2024年第2期43卷 562-574页

作者： Jia-Xin Chen Guo-Qiang Zhang Xian-Ying Qin Kui li. Zi-Jin Yang Ge-Meng li.ng Yue Xia Guo-Bin Zhang hai-Kun Wu Qiu-Chan Cai hai li. Bao-Hua li Shenzhen Key Laboratory on Power Battery Safety Research and Shenzhen Geim Graphene Center Tsinghua Shenzhen International Graduate SchoolShenzhen518055China Shenzhen Graphene Innovation Center Co. Ltd.Shenzhen518107China School of Chemical Engineering and Advanced Materials The University of AdelaideAdelaideSA5005Australia Department of Chemistry City University of Hong KongHong Kong990077China

Uncontrolled growth of li.hium dendrite will lead to low Coulombic efficiency and poor cycle stabili.y,which hinders the commerciali.ation of li.hium metal ***,a novel modified li.hium anode with reduced graphene oxide conductive network containing trace li.hiophili. phosphorus(P-rGO/Cu)is prepared by electrospraying technique combined with heat treatment *** rGO layer has a concave and undulating conductive structure,which can significantly improve the effective electrical contact between li.hium metal and the current collector,speed up the kinetics of interfacial electron transport and reaction,and improve the resistance of the negative electrode to the internal stress caused by volume change of the li.hium,which is advantageous for the stabili.y of the SEI *** extremely small and uniformly distributed red phosphorus element avoids the volume change caused by li.hiation to the maximum *** two-phase compound li.(3)P obtained by alloying P with li.can directionally induce the homogeneous nucleation and dense deposition of li.hium metal,address the issue of li.hium dendrites and extend the cycle li.e of the *** obtained P-rGO/Cu exhibits excellent electrochemical performance with an average Coulombic efficiency(CE)of 98%at a current density of 1 mA·cm^(−2) for 400 cycles,and the capacity retention rate of the full cell matched with li.hium iron phosphate(LFP)is 83%after 400 cycles at 1C.

关键词： li.hium anode Dendrite-free li.hiophili.ity Induced nucleation deposition

A Rendezvous Mission to the Second Earth Trojan Asteroid 2020 XL_5 with Low-Thrust Multi-Gravity Assist Techniques

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Research in Astronomy and Astrophysics 2024年第1期24卷 245-264页

作者： Shi-hai Yang Bo Xu Xin li School of Aeronautics and Astronautics Sun Yat-sen UniversityShenzhen 518107China

As the second of Earth's Trojan asteroids, 2020 XL_(5) is worthy of rendezvous and even sample return missions in many aspects. In this paper, a rendezvous mission to Earth's second Trojan asteroid 2020 XL_(5) is ***, due to its high incli.ation and large eccentricity, direct impulsive transfer requires large amounts of fuel consumption. To address this challenge, we explore the benefits of electric propulsion and multi-gravity assist techniques for interplanetary missions. These two techniques are integrated in this mission design. The design of a low-thrust gravity-assist(LTGA) trajectory in multi-body dynamics is thoroughly investigated,which is a complex process. A comprehensive framework including three steps is presented here for optimization of LTGA trajectories in multi-body dynamics. The rendezvous mission to 2020 XL_(5) is designed with this three-step approach. The most effective transfer sequence among the outcomes involves Earth–Venus–Earth–Venus-2020 XL_(5). Numerical results indicate that the combination of electric propulsion and multi-gravity assists can greatly reduce the fuel consumption, with fuel consumption of 9.03%, making it a highly favorable choice for this rendezvous mission.

关键词： minor planets asteroids:general celestial mechanics Planetary Systems

Cascade electrolysis and thermocatalysis: a reli.ble system for upgrading C1 to C4 hydrocarbons

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Rare Metals 2024年第1期43卷 410-412页

作者： Chao-Yue Sun Wen li.hai-Qing Wang Institute for Advanced Interdiscipli.ary Research(iAIR) College of Chemistry and Chemical EngineeringUniversity of JinanJinan 250022China

The carbon cycle is important for maintaining a stable cli.ate and carbon balance on Earth. Renewable-electricitydriven upcycli.g of carbon dioxide (CO_(2)) into value-added multi-carbon molecules is a potentially sus... 详细信息

关键词： cycli.g hydrocarbons enable

Precise immobili.ation of metal single atoms into a porphyrinic metal-organic framework for an efficient alkene hydrosilylation

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Nano Research 2024年第7期17卷 5914-5921页

作者： Chun-Ying Chen Qi-Jie Mo Fu-Zhen li.hai-li.Song li.Zhang MOE Laboratory of Bioinorganic and Synthetic Chemistry Lehn Institute of Functional MaterialsSchool of ChemistrySun Yat-Sen UniversityGuangzhou 510006China

Alkene hydrosilylation is one of the most concise and atom-economical methods to synthesize organosili.on ***,we reported the precise immobili.ation of metal single atoms(M-SAs;M=Ru,Rh,Ir,Pd,Pt,and Au)into a porphyrinic metalorganic framework(MOF)of PCN-222(PCN=porous coordination network),and then appli.d the resultant MOF composites of M-SAs@PCN-222 to alkene *** solvent-free conditions,Pt-SAs@PCN-222 displayed an especially high catalytic efficiency with the turnover frequency up to 119 s−1 and the maximum turnover number of 906,250 at room *** and theoretical studies revealed that there existed strong interactions between Pt-SAs@PCN-222 and the substrates,which helped to condense the substrates in the cavities of the porous *** density functional theory calculations and molecular dynamics simulations disclosed that PCN-222 could transfer electrons to Pt-SAs to enhance the silane oxidative addition and drive the reaction to proceed smoothly via Chalk–Harrod pathway.

关键词： alkene hydrosilylation single atom catalysts metal-organic frameworks precision chemistry synergistic catalysis

Yemazhui(Herba Eupatorii li.dleyani)ameli.rates li.opolysaccharide-induced acute lung injury via modulation of the toll-li.e receptor 4/nuclear factor kappa-B/nod-li.e receptor family pyrin domain-containing 3 protein signali.g pathway and intestinal flor

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Journal of Traditional Chinese Medicine 2024年第2期44卷 303-314页

作者： REN li.hai Yang YANG Xue LUO Xianqin Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metaboli. Diseases College of Traditional Chinese MedicineChongqing Medical UniversityChongqing 400016China College of Basic Medicine Chongqing Medical UniversityChongqing 400016China

OBJECTIVE:To investigate the impact of Yemazhui(Herba Eupatorii li.dleyani,HEL)against li.opolysaccharide(LPS)-induced acute lung injury(Ali.and explore its underlying mechanism in ***:The chemical constituents of HEL were analyzed by ultra-high performance li.uid chromatographyquadrupole time-of-fli.ht mass spectrometry ***,HEL was found to suppress LPS-induced Ali.in ***-week-old male Sprague-Dawley rats were randomly divided into 6 groups:control,LPS,Dexamethasone(Dex),HEL low dose 6 g/kg(HEL-L),HEL medium dose 18 g/kg(HEL-M)and HEL high dose 54 g/kg(HEL-H)*** model rats were intratracheally injected with 3 mg/kg LPS to establi.h an Ali.*** counts,lung wet/dry weight ratio,as well as myeloperoxidase(MPO)activity were determined followed by the detection with hematoxyli. and eosin staining,enzyme li.ked immunosorbent assay,quantitative real time polymerase chain reaction,western blotting,immunohistochemistry,and ***,to explore the effect of HEL on Ali.mediated intestinal flora,we performed 16s rRNA sequencing analysis of intestinal ***:HEL attenuated LPS-induced inflammation in lung tissue and intestinal flora *** study indicated that HEL suppressed the lung coefficient and wet/dry weight ratio of LPS-induced Ali.in rats,inhibited leukocytes exudation and MPO activity,and improved the pathological injury of lung *** addition,HEL reduced the expression of tumor necrosis factoralpha,interleukin-1beta(IL-1β)and interleukin-6(IL-6)in bronchoalveolar lavage fluid and serum,and inhibited nuclear displacement of nuclear factor kappa-B p65(NF-κBp65).And 18 g/kg HEL also reduced the expression levels of toll-li.e receptor 4(TLR4),myeloid differentiation factor 88,NF-κBp65,phosphorylated inhibitor kappa B alpha(phospho-IκBα),nod-li.e receptor family pyrin domain-containing 3 protein(NLRP3),IL-1β,and interleukin-18(IL-18)in lung tissue,and regulated intestinal flora disturban

关键词： Yemazhui(Herba Eupatorii li.dleyani) acute lung injury anti-inflammation toll-li.e receptor 4 nuclear factor kappa-B nod-li.e receptor family pyrin domain-containing 3 protein signal transduction gastrointestinal microbiome