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An Algorithm for Output Spectrum Analysis of Nonlinear System with Correlative Sources Based on Power Series

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Chinese Journal of Electronics 2021年第3期30卷 542-548页

作者： xu hui SU Donglin The School of Electronic and Information Engineering Beihang University The Research Institute for Frontier Science Beihang University

An algorithm for output spectrum analysis of nonlinear system with correlative sources is ***, the output terms of nonlinear system are analyzed based on the power series. Then, the algorithm is proposed. In the proposed method, different terms with the same frequency are picked out and added together by considering different phases, and the amplitudes of the output spectrum are obtained from the summarized results. Two numerical examples are used to verify the proposed algorithm. It is found that the amplitudes of output spectrum vary with different combinations of phases. Finally, the proposed algorithm is applied to control the output spectrum. Results show that the output amplitude of a specific frequency can be suppressed through changing both the amplitudes and the phases of the input signals.

关键词： output amplitude correlative sources output spectrum analysis spectral analysis nonlinear system power series

Dual ligands relay-promoted transformation of unstrained ketones to polyfluoroarenes and nitriles

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Science China Chemistry 2023年第7期66卷 2037-2045页

作者： Zhen-Yu Wang huiying xu xu Zhang Xing Wang hui xu hui Gao hui-Xiong Dai School of Chinese Materia Medica Nanjing University of Chinese MedicineNanjing 210023China CAS Key Laboratory of Receptor Research State Key Laboratory of Drug ResearchShanghai Institute of Materia MedicaChinese Academy of SciencesShanghai 201203China School of Pharmaceutical Sciences Guangzhou Medical UniversityGuangzhou 511436China University of Chinese Academy of Sciences Beijing 100049China

C-C bond activation has emerged as a powerful tool for the construction of complex ***,we report a dual ligands relay-promoted transformation of unstrained aryl,alkenyl and alkynyl ketones to the corresponding polyfluoroarenes and nitriles via C-C(=O)bond cleavage and subsequent decarboxylative arylation *** polyfluoroarene and nitrile products are obtained in one pot under cyanide-free *** protocol features high atom economy,broad functional group tolerance and excellent heterocyclic *** late-stage functionalization of the drug and natural product demonstrated the synthetic utility of our ***,the decisive role of the dual ligands was clarified and the mechanistic rationale including theβ-C elimination as the rate-limiting step was supported by detailed density functional theory(DFT)studies.

关键词： C-C bond activation dual ligands relay unstrained ketones modification of drugs and natural products DFT study

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Real-time Feed-forward Force Compensation for Active Magnetic Bearings System Based on H∞ Controller

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Chinese Journal of Mechanical Engineering 2011年第1期24卷 58-66页

作者： GAO hui xu Longxiang College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

There are two kinds of unbalance vibrations—force vibration and displacement vibration due to the existence of unbalance excitation in active magnetic bearings（AMB） system. And two unbalance compensation methods—closed-loop feedback and open loop feed-forward are presented to reduce the force vibration. The transfer function order of the control system directly influencing the system stability will be increased when the closed-loop method is adopted, which makes the real-time compensation not easily achieved. While the open loop method would not increase the primary transfer function order, it provides conditions for real-time compensation. But the real-time compensation signals are not easy to be obtained in the open loop method. To implement real-time force compensation, a new method is proposed to reduce the force vibration caused by the rotor unbalance on the basis of AMB active control. The method realizes real-time and on-line force auto-compensation based on H∞ controller and one novel feed-forward compensation controller, which makes the rotor rotate around its inertia axis. The time-variable feed-forward compensatory signal is provided by a modified adaptive variable step-size least mean square（VSLMS） algorithm. And the relevant least mean square（LMS） algorithm parameters are used to solve the H∞ controller weighting functions. The simulation of the new method to compensate some frequency-variable and sinusoidal signals is completed by MATLAB programming, and real-time compensation is implemented in the actual AMB experimental system. The simulation and experiment results show that the compensation scheme can improve the robust stability and the anti-interference ability of the whole AMB system by using H∞ controller to achieve close-loop control, and then real-time force unbalance compensation is implemented. The proposed research provides a new control strategy containing real-time algorithm and H∞ controller for the force compensation of AMB system. And

关键词： active magnetic bearings H∞ robust controller sensitivity and complementary sensitivity VSLMS algorithm feed-forward compensation

Selective and Sensitive Fluorescent Chemosensors for Cu2＋ Ion Based upon Bis-1,8-naphthalimide Dyads

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Chinese Journal of Chemistry 2012年第2期30卷 267-272页

作者： Dai,huiling xu,hui Laboratory of Pharmaceutical Design&Synthesis College of ScienceNorthwest Agrieulture&Forestry UniversityYanglingShaanxi 712100China

A series of new fluorescent chemosensors 5a--5e, composed of two aminonaphthalimide fluorophores and 2,6-bis（（N-aminoalkyl）aminocarboxy）pyridines, were prepared, characterized, and their fluorescent properties to- wards heavy and transition metal （HTM） ions were investigated. Chemosensors 5e--Se exhibited high selectivity and sensitivity for Cu2＋ ion over other HTM ions with fluorescent quenching （green to colourless）. It clearly demonstrated that the length of the linkers （diamines） between the aminonaphthalimides and 2,6-dicarboxypyridine of 5a--Se was very important for their sensitivity and selectivity for Cu2~ ion over other HTM ions.

关键词： fluorescence sensors 1,8-naphthalimide metal ion selectivity

Pressure-induced bimetallic carbon nanotubes from metalorganic frameworks as optimized bifunctional electrocatalysts for water splitting

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Rare Metals 2023年第1期42卷 155-164页

作者： Hong-xu Chen hui xu Zhi-Rong Song Yi Liu hui Cui Jun-Kuo Gao Key Laboratory of Rare Earth Optoelectronic Materials and Devices of Zhejiang Province Institute of Optoelectronic Materials and DevicesCollage of Optical and Electronic TechnologyChina Jiliang UniversityHangzhou310018China Institute of Functional Porous Materials School of Materials Science and EngineeringZhejiang Sci-Tech UniversityHangzhou310018China Institute for Composites Science Innovation School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China Argonne National Laboratory Physics DivisionLemontIL60439USA Department of Chemistry and International Institute for Nanotechnology(IIN) Northwestern UniversityEvanstonIL60208USA

Carbon nanotubes(CNTs)have attracted great interest in numerous applications due to their excellent electronic and structural ***,harsh synthesis conditions and high energy consumption limit the further application of ***,we developed a facile and innovative strategy to generate CNTs by physically pressurizing metal-organic frameworks(MOFs)and then *** synthesized bimetallic nitrogen/sulfur double-doped carbon nanotubes are denoted as Fe_(x)Co_(1-x)P(x=0.5,0.6,0.7,0.8,0.9).The introduction of pressure not only revolutionized the morphology of the electrocatalysts,but also enhanced the activity of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)in alkaline ***_(0.6)Co_(0.4)-P exhibits superior OER and HER performances in 1.0 mol·L^(-1)KOH solution with overpotentials of 364 and 346 mV at 10 mA·cm^(-2),which are 28 and 5 mV lower than unpressurized Fe0.6Co0.4.

关键词： Metal-organic frameworks(MOFs) Carbon nanotubes(CNTs) Bifunctional Pressurizing Oxygen evolution reaction(OER) Hydrogen evolution reaction(HER)

Deep reinforcement learning in fluid mechanics:A promising method for both active flow control and shape optimization

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Journal of Hydrodynamics 2020年第2期32卷 234-246页

作者： Jean Rabault Feng Ren Wei Zhang hui Tang hui xu Department of Mathematics University of OsloOsloNorway Research Center of Fluid Structure Interactions Department of Mechanical Engineering Hong Kong Polytechnical UniversityHong KongChina Science and Technology on Water Jet Propulsion Laboratory Marine Design and Research Institute of ChinaShanghai200011China School of Aeronautic and Astronautic Shanghai Jiao Tong UniversityShanghai200011China Department of Aeronautics Imperial College LondonLondonUK

In recent years,artificial neural networks(ANNs)and deep learning have become increasingly popular across a wide range of scientific and technical fields,including fluid *** it will take time to fully grasp the potentialities as well as the limitations of these methods,evidence is starting to accumulate that point to their potential in helping solve problems for which no theoretically optimal solution method is *** is particularly true in fluid mechanics,where problems involving optimal control and optimal design are ***,such problems are famously difficult to solve effectively with traditional methods due to the combination of non linearity,non convexity,and high dimensionality they *** contrast,deep reinforcement learning(DRL),a method of optimization based on teaching empirical strategies to an ANN through trial and error,is well adapted to solving such *** this short review,we offer an insight into the current state of the art of the use of DRL within fluid mechanics,focusing on control and optimal design problems.

关键词： Machine learning deep reinforcement learning(DRL) flow control

Chemically synthesizing exchange-coupled SmCo_(5)/Sm_(2)Co_(17) nanocomposites

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Rare Metals 2021年第3期40卷 575-581页

作者： Yao-hui xu Qiang Jiang Kun Li Zhen-hui Ma School of Physics and Electronic Engineering Laboratory for Functional MaterialsLeshan Normal UniversityNanjing 211189China Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments School of Mechanical EngineeringSoutheast UniversityNanjing 211189China College of Materials Science and Engineering Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of TechnologyBeijing 100124China Department of Chemistry Brown UniversityProvidenceRI 02912USA

A new strategy to chemically synthesize exchange-coupled SmCo_(5)/Sm_(2) Co_(17) nanocomposites by in situ decomposition of SmCox(5 详细信息

A new strategy to chemically synthesize exchange-coupled SmCo_(5)/Sm_(2) Co_(17) nanocomposites by in situ decomposition of SmCox(5

关键词： SmCo_(5) Nanocomposites Exchange coupling Coercivity

A Middle Triassic stem-neopterygian fish from China sheds new light on the peltopleuriform phylogeny and internal fertilization

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Science Bulletin 2016年第22期61卷 1766-1774页

作者： Guang-hui xu Xin-Ying Ma Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences

Internal fertilization and viviparity are easily observed and well studied in living neopterygian fishes(14teleostean families), but they are difficult to identify in extinct taxa due to the limitation of the fossil record. The Peltopleuriformes from the Middle to Late Triassic of Europe and South China are a stem group of Neopterygii that may have first evolved internal fertilization and viviparity in this clade because they show a highly modified anal fin in presumed males resembling the intromittent organ in living viviparous teleosts. Until recently, Peltopleurus lissocephalus and P. rugosus from the Ladinian/Anisian boundary(*242 Ma) of Monte San Giorgio area in Switzerland and Italy represent the oldest record of Peltopleuriformes, and the phylogenetic interrelationships of this group remain controversial. Here, we report the discovery of a new peltopleuriform, Peltopleurus nitidus sp. nov., based on eleven well-preserved specimens from the early Middle Triassic(Pelsonian, Anisian, *244 Ma)of Luoping, eastern Yunnan, China. The discovery documents the oldest convincing peltopleuriform, extending the geological range of this clade by proximately two million years. Results of the phylogenetic analysis recover *** at the base of Peltopleuridae, and provide robust support for the sister-group relationships of Peltopleuridae with Thoracopteridae within the Peltopleuriformes. The male anal fin of P. nitidus shows a primitive condition unknown in other peltopleuriforms. Comparative studies of the male anal fin in P. nitidus and other peltopleuriforms shed new light on the internal fertilization in this group.

关键词： Sexual dimorphism Viviparity Peltopleuridae Thoracopteridae Triassic

QPSO-based algorithm of CSO joint infrared super-resolution and trajectory estimation

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Journal of Systems Engineering and Electronics 2011年第3期22卷 405-411页

作者： Liangkui Lin hui xu Dan xu Wei An Kai Xie School of Electronics and Engineering National University of Defense TechnologyChangsha 410073P.R.China Unit 94810 of the PLA Nanjing 210007P.R.China Artillery Academy of the PLA Hefei 230031P.R.China

The midcourse ballistic closely spaced objects（CSO） create blur pixel-cluster on the space-based infrared focal plane,making the super-resolution of CSO quite necessary.A novel algorithm of CSO joint super-resolution and trajectory estimation is *** algorithm combines the focal plane CSO dynamics and radiation models,proposes a novel least square objective function from the space and time information,where CSO radiant intensity is excluded and initial dynamics（position and velocity） are chosen as the model ***,the quantum-behaved particle swarm optimization（QPSO） is adopted to optimize the objective function to estimate model parameters,and then CSO focal plane trajectories and radiant intensities are ***,the estimated CSO focal plane trajectories from multiple space-based infrared focal planes are associated and filtered to estimate the CSO stereo ballistic ***,the performance（CSO estimation precision of the focal plane coordinates,radiant intensities,and stereo ballistic trajectories,together with the computation load） of the algorithm is tested,and the results show that the algorithm is effective and feasible.

关键词： super-resolution trajectory estimation closely spaced object(CSO) midcourse ballistic infrared focal plane quantumbehaved particle swarm optimization(QPSO).