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A general principle enabling the design of ultrastable metal nanocatalysts

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Science China Chemistry 2022年第4期65卷 641-642页

作者： xin xu Collaborative Innovation Center of Chemistry for Energy Materials ShanghaiKey Laboratory of Molecular Catalysis and Innovative MaterialsMOE Key Laboratory of Computational Physical SciencesShanghai Key Laboratory of Bioactive Small MoleculesDepartment of ChemistryFudan UniversityShanghai 200433China

The design and the development of catalysts with high activity,high selectivity and high stability are of great significance for improving the efficiency of catalytic reactions,saving energy and reducing consumption,which is particularly important for achieving the dual-carbon *** development and the guidance of advanced catalytic theories are urgently needed[1].The Sabatier’s principle of catalyst activity states that the interaction between the reactants and the catalyst should not be too strong or too *** one of the basic theories of heterogeneous catalysis developed on this basis in the past century,it has profoundly affected the design of modern catalysts[2].

关键词： catalyst catalysis reactant

Interference Suppression and Jitter Elimination Ability-Based Adaption Tracking Guidance for Robotic Fishes

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IEEE/CAA Journal of Automatica Sinica 2025年第1期 126-137页

作者： Dongfang Li Jie Huang Rob Law xin xu Limin Zhu Edmond Q.Wu IEEE the School of Electrical Engineering and Automation Fuzhou University the Key Laboratory of System Control and Information Processing Ministry of Education the School of Electrical Engineering and Automation Fuzhou University 5G+Industrial Internet Institute Fuzhou University the University of Macau the College of Mechatronics and Automation National University of Defense Technology the School of Mechanical Engineering Shanghai Jiao Tong University the Department of Computer Science and Engineering Shanghai Jiao Tong University

This work presents an adaptive tracking guidance method for robotic fishes. The scheme enables robots to suppress external interference and eliminate motion jitter. An adaptive integral surge line-of-sight guidance rule is designed to eliminate dynamics interference and sideslip issues. Limited-time yaw and surge speed observers are reported to fit disturbance variables in the model. The approximation values can compensate for the system's control input and improve the robots' tracking ***, this work develops a terminal sliding mode controller and third-order differential processor to determine the rotational torque and reduce the robots' run jitter. Then, Lyapunov's theory proves the uniform ultimate boundedness of the proposed method. Simulation and physical experiments confirm that the technology improves the tracking error convergence speed and stability of robotic fishes.

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Toward an Understanding of the Periastron Puzzle of PSR B1259-63

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Chinese Journal of Astronomy and Astrophysics 2006年第5期6卷 572-578页

作者： Ren-xin xu Department of Astronomy School of Physics Peking University Beijing 100871

Efforts are made to understand the timing behaviors （e.g., the jumps in the projected pulsar semimajor axis at the periastron passages） observed in the 13-year monitoring of PSR B1259-63. Planet-like objects are suggested to orbit around the Be star, which may gravitationally perturb the （probably low mass） pulsar when it passes through periastron. An accretion disk should exist outside the pulsar＇s light cylinder, which creates a spindown torque on the pulsar due to the propeller effect. The observed negative braking index and the discrepant timing residuals close to periastron could be related to the existence of a disk with a varying accretion rate. A speculation is presented that the accretion rate may increase on a long timescale in order to explain the negative braking index.

关键词： pulsars individual PSR B1259-63 -- binaries general -- stars neutron -- stars early-type

A solution to the puzzling symbiotic X-ray system 4U 1700+24

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Research in Astronomy and Astrophysics 2014年第6期14卷 617-624页

作者： Ren-xin xu School of Physics and State Key Laboratory of Nuclear Physics and Technology and Kavli Institute for Astronomy and Astrophysics Peking University

A circumstellar corona is proposed to explain a strange quark-cluster star during an accretion phase, which could be essential for understanding the observa- tions of the puzzling symbiotic X-ray system 4U 1700＋24. The state of cold matter at supranuclear density is still an important matter of debate, and one of the con- sequences of a strange star acting as a pulsar is the self-bound phenomenon on the surface, which makes extremely low-mass compact objects unavoidable. In principle, both the redshifted O VIII Ly-c~ emission line and the change in the blackbody radi- ation area could naturally be understood if 4U 1700＋24 is a low-mass quark-cluster star which exhibits wind accretion.

关键词： pulsars: individual (4U 1700+24) -- dense matter -- stars: neutron

Distributed emitter parameter refinement based on maximum likelihood

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International Journal of Intelligent Computing and Cybernetics 2017年第1期10卷 2-11页

作者： xin xu Science and Technology on Information System Engineering Laboratory Nanjing Research Institute of Electronic EngineeringNanjingChina

Purpose-Emitter parameter estimation via signal sorting is crucial for communication,electronic reconnaissance and radar intelligence ***,due to problems of transmitter circuit,environmental noises and certain unknown interference sources,the estimated emitter parameter measurements are still inaccurate and *** a result,it is indispensable to further refine the parameter *** the benchmark clustering algorithms are assumed to be capable of inferring the true parameter values by discovering cluster centers,the high computational and communication cost makes them difficult to adapt for distributed learning on massive measurement *** paper aims to discuss these ***/methodology/approach-In this work,the author brings forward a distributed emitter parameter refinement method based on maximum *** author’s method is able to infer the underlying true parameter values from the huge measurement data efficiently in a distributed working ***-Experimental results on a series of synthetic data indicate the effectiveness and efficiency of the author’s method when compared against the benchmark clustering ***/value-With the refined parameter values,the complex stochastic parameter patterns could be discovered and the emitters could be identified by merging observations of consistent parameter values ***,the author is in the process of applying her distributed parameter refinement method for PRI parameter pattern discovery and emitter *** superior performance ensures its wide application in both civil and military fields.

关键词： Data mining Distributed learning Maximum likelihood Parameter refinement Paper type Research paper

A new type of adiabatic invariants for disturbed non-conservative nonholonomic system

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Chinese Physics B 2019年第12期28卷 118-122页

作者： xin-xin xu Yi Zhang College of Mathematics and Physics Suzhou University of Science and TechnologySuzhou 215009China College of Civil Engineering Suzhou University of Science and TechnologySuzhou 215011China

According to the Herglotz variational principle and differential variational principle of Herglotz type, we study the adiabatic invariants for a non-conservative nonholonomic system. Firstly, the differential equations of motion of the non-conservative nonholonomic system based upon the generalized variational principle of Herglotz type are given, and the exact invariant for the non-conservative nonholonomic system is introduced. Secondly, a new type of adiabatic invariant for the system under the action of a small perturbation is obtained. Thirdly, the inverse theorem of the adiabatic invariant is given. Finally, an example is given.

关键词： non-conservative nonholonomic mechanics adiabatic invariants differential variational principle of Herglotz type

Compatibilization of PBT/PP Blends by Adding Side-chain Liquid Crystalline Ionomer with Quaternary Pyridinium Groups

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Chemical Research in Chinese Universities 2011年第1期27卷 140-144页

作者： xu xin-yu Department of Polymer Materials and Engineering School of Chemistry and Materials Science Liaoning Shihua University Fushun 113001 P R. China

A side-chain liquid crystalline ionomer（SLCI） was synthesized by grafting copolymerization of 4-（4-ethoxybenzoyloxy）-4＇-allyloxybiphenyl and N-allyl-pyridium bromide on polymethylhydrosiloxane. The SLCI was blended with polypropylene（PP） and polybutylene terephthalate（PBT） by melt mixing. The thermal behavior, liquid crystalline properties, morphological structure, and mechanical properties of the blends were investigated by differential scanning calorimetry（DSC）, polarizing optical microscopy（POM）, scanning electron microscopy（SEM）, and tensile measurement. When a proper amount of SLCI was added, fine configurations were formed in the PBT/PP/SLCI blend system, and the mechanical properties were improved due to improved adhesion at the interface. When excess SLCI was added, an inhomogeneous structure resulted, which caused the mechanical properties to deteriorate.

关键词： Poly(butylent terephthalate) Poly(propylene) Liquid crystalline ionomer Compatibilization

Rare-earth mediated dihydrogen activation and catalytic hydrogenation

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Journal of Rare Earths 2021年第9期39卷 1017-1023页

作者： Yiwen Guan Erli Lu xin xu Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials ScienceSoochow UniversitySuzhou 215123China School of Natural and Environmental Sciences Newcastle UniversityKing's RoadNewcastle Upon TyneNE17RUUK

This review covers H-H bond cleavage of dihydrogen(H2)mediated by structurally well-defined rareearth metal(scandium,yttrium and lanthanides)complexes,and their applications in homogenous catalysis,such as catalytic hydrogenation of unsaturated organic *** on the mechanism of the H-H bond cleavage,this review is organized in two parts:(1)σ-bond metathesis,and(2)non-σ-metathesis H2 *** latter is a new trend in this research field and is the emphasis of this *** H2 into inorganic rare-earth polyhydride complexes,albeit their potential applications as hydrogen-storage materiel,is not in the scope of this review.

关键词： Rare earths Dihydrogen activation Hydrogenation Homogeneous catalysis Cooperative effect

Several fourth-order force gradient symplectic algorithms

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Research in Astronomy and Astrophysics 2010年第2期10卷 173-188页

作者： Jia xu xin Wu Department of Physics Nanchang University Nanchang 330031 China

By adding force gradient operators to symmetric compositions, we build a set of explicit fourth-order force gradient symplectic algorithms, including those of Chin and coworkers, for a separable Hamiltonian system with quadratic kinetic en- ergy T and potential energy V. They are extended to solve a gravitational n-body Hamiltonian system that can be split into a Keplerian part H0 and a perturbation part H1 in Jacobi coordinates. It is found that the accuracy of each gradient scheme is greatly superior to that of the standard fourth-order Forest-Ruth symplectic integra- tor in T ＋ V-type Hamiltonian decomposition, but they are both almost equivalent in the mean longitude and the relative position for H0 ＋//1-type decomposition. At the same time, there are no typical differences between the numerical performances of these gradient algorithms, either in the splitting of T ＋ V or in the splitting of H0 ＋//1. In particular, compared with the former decomposition, the latter can dra- matically improve the numerical accuracy. Because this extension provides a fast and high-precision method to simulate various orbital motions of n-body problems, it is worth recommending for practical computation.

关键词： celestial mechanics -- methods: numerical