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nonlinear dynamics of a circular curved cantilevered pipe conveying pulsating fluid based on the geometrically exact model

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 261-276页

作者： Runqing CAO Zilong GUO Wei CHEN Huliang DAI Lin WANG Department of Engineering Mechanics School of Aerospace EngineeringHuazhong University of Science and TechnologyWuhan 430074China Hubei Key laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074China State Key laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Due to the novel applications of flexible pipes conveying fluid in the field of soft robotics and biomedicine,the investigations on the mechanical responses of the pipes have attracted considerable *** fluid-structure interaction(FSI)between the pipe with a curved shape and the time-varying internal fluid flow brings a great challenge to the revelation of the dynamical behaviors of flexible pipes,especially when the pipe is highly flexible and usually undergoes large *** this work,the geometrically exact model(GEM)for a curved cantilevered pipe conveying pulsating fluid is developed based on the extended Hamilton's *** stability of the curved pipe with three different subtended angles is examined with the consideration of steady fluid *** attention is concentrated on the large-deformation resonance of circular pipes conveying pulsating fluid,which is often encountered in practical *** constructing bifurcation diagrams,oscillating shapes,phase portraits,time traces,and Poincarémaps,the dynamic responses of the curved pipe under various system parameters are *** mean flow velocity of the pulsating fluid is chosen to be either subcritical or *** numerical results show that the curved pipe conveying pulsating fluid can exhibit rich dynamical behaviors,including periodic and quasi-periodic *** is also found that the preferred instability type of a cantilevered curved pipe conveying steady fluid is mainly in the flutter of the second *** a moderate value of the mass ratio,however,a third-mode flutter may occur,which is quite different from that of a straight pipe system.

关键词： curved pipe conveying fluid pulsating fluid geometrically exact model(GEM) nonlinear dynamics parametric vibration flutter

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Ultra-robust informational metasurfaces based on spatial coherence structures engineering

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Light(science & Applications) 2024年第7期13卷 1310-1319页

作者： Leixin Liu Wenwei Liu Fei Wang Xiaofeng Peng Duk-Yong Choi Hua Cheng Yangjian Cai Shuqi Chen Shandong Provincial Engineering and Technical Center of Light Manipulations Collaborative Innovation Center of Light Manipulation and ApplicationsShandong Provincial Key Laboratory of Optics and Photonic DeviceSchool of Physics and ElectronicsShandong Normal UniversityJinan 250014China. The Key laboratory of Weak Light nonlinear Photonics Ministry of EducationSchool of PhysicsSchool of Materials Science and EngineeringSmart Sensing Interdisciplinary Science CenterNankai UniversityTianjin 300071China. School of Physical science and Technology Soochow UniversitySuzhou 215006China. Laser Physics Centre Research School of PhysicsAustralian National UniversityCanberraACT 2601Australia. The Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuanShanxi 030006China

Optical information transmission is vital in modern optics and photonics due to its concurrent and multi-dimensional nature,leading to tremendous applications such as optical microscopy,holography,and optical *** optical information transmission technologies suffer from bulky optical setup and information loss/crosstalk when meeting scatterers or obstacles in the light ***,we theoretically propose and experimentally realize the simultaneous manipulation of the coherence lengths and coherence structures of the light beams with the disordered *** ultra-robust optical information transmission and self-reconstruction can be realized by the generated partially coherent beam with modulated coherence structure even 93%of light is recklessly obstructed during light transmission,which brings new light to robust optical information transmission with a single *** method provides a generic principle for the generalized coherence manipulation on the photonic platform and displays a variety of functionalities advancing capabilities in optical information transmission such as meta-holography and imaging in disordered and perturbative media.

关键词： optics coherent holography

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Neural-network-based fully distributed formation control for nonlinear multi-agent systems with event-triggered communication

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science China(Technological sciences) 2024年第1期67卷 209-220页

作者： ZHU GuoLiang LIU KeXin GU HaiBo LÜJinHu School of Automation science and Electrical Engineering Beihang UniversityBeijing 100191China Zhongguancun laboratory Beijing 100094China

This paper investigates the consensus-based formation control problem for multi-agent systems with unknown nonlinear *** achieve the desired formation,we propose two formation controllers to achieve the desired formation,one based on system states and the other on system *** proposed controllers utilize adaptive gains to avoid global information and neural networks to estimate and compensate for *** proposed event-triggered schemes avoid continuous communication among agents and exclude the Zeno *** analysis reveals that formation errors are bounded,and numerical simulations are used to validate the effectiveness of the proposed approaches.

关键词： formation control neural network adaptive control event-triggered communication multi-agent systems

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Design and Implementation of nonlinear Precoding for MIMO-SDMA Toward 6G Wireless

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China Communications 2024年第1期21卷 69-87页

作者： Chaowu Wu Yue Xiao Shu Fang Gang Wu National Key laboratory of Wireless Communications University of Electronic Science and Technology of ChinaChengdu 611731China

In this paper,we present a novel and robust nonlinear precoding(NLP)design and detection structure specifically tailored for multiple-input multipleoutput space division multiple access(MIMO-SDMA)systems toward 6G *** approach aims to effectively mitigate the impact of imperfect channel estimation by leveraging the channel fluctuation mean square error(MSE)for reconstructing a highly accurate precoding matrix at the ***,we introduce a simplified receiver structure that eliminates the need for equalization,resulting in reduced interference and notable enhancements in overall system *** conduct both computer simulations and experimental tests to validate the efficacy of our proposed *** results reveals that the proposed NLP scheme offers significant performance improvements,making it particularly well-suited for the forthcoming 6G wireless.

关键词： MIMO-SDMA nonlinear precoding Tomlinson-Harashima precoding(THP) vector perturbation(VP)

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Deep-learning-empowered synthetic dimension dynamics: morphing of light into topological modes

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Advanced Photonics 2024年第2期6卷 61-68页

作者： Shiqi Xia Sihong Lei Daohong Song Luigi Di Lauro Imtiaz Alamgir Liqin Tang Jingjun Xu Roberto Morandotti Hrvoje Buljan Zhigang Chen Nankai University TEDA Institute of Applied Physics School of Physics The MOE Key Laboratory of Weak-Light Nonlinear Photonics Shanxi University Collaborative Innovation Center of Extreme Optics INRS-EMT University of Zagreb Department of PhysicsFaculty of Science

Synthetic dimensions(SDs) opened the door for exploring previously inaccessible phenomena in high-dimensional space. However, construction of synthetic lattices with desired coupling properties is a challenging and unintuitive task. Here, we use deep learning artificial neural networks(ANNs) to construct lattices in real space with a predesigned spectrum of mode eigenvalues, and thus to validly design the dynamics in synthetic mode dimensions. By employing judiciously chosen perturbations(wiggling of waveguides at desired frequencies), we show resonant mode coupling and tailored dynamics in SDs. Two distinct examples are illustrated: one features uniform synthetic mode coupling, and the other showcases the edge defects that allow for tailored light transport and confinement. Furthermore, we demonstrate morphing of light into a topologically protected edge mode with modified Su–Schrieffer–Heeger photonic lattices. Such an ANN-assisted construction of SDs may advance toward “utopian networks,” opening new avenues for fundamental research beyond geometric limitations as well as for applications in mode lasing,optical switching, and communication technologies.

关键词： synthetic dimensions deep learning mode manipulation topological mode morphing photonic lattices

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Distortion-aware beamforming design for multi-beam satellite communications with nonlinear power amplifiers

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science China(Information sciences) 2024年第6期67卷 359-369页

作者： Xiang XIAO Li YOU Kezhi WANG Xiqi GAO National Mobile Communications Research laboratory Southeast University Purple Mountain Laboratories Department of Computer science Brunel University London

Hardware components can cause different impairments, including power amplifier(PA) nonlinearities, which inevitably impact the system performance of satellite communications(SATCOM). In this work, we consider a multi-beam SATCOM downlink system and investigate the distortion-aware beamforming scheme with the characteristics of PA non-linearities. Notably, we aim to maximize the resource efficiency(RE), defined as the weighted sum of energy efficiency(EE) with spectral efficiency(SE), to obtain a flexible EE-SE tradeoff while accounting for the characteristics of PA distortion and the total power *** that the optimization objective is a sum of ratios and the high non-convexity involved in constraints,we propose an efficient approach that exploits the quadratic transformation, the Lagrange multiplier method,and the gradient ascent approach to handle this issue. Simulation results demonstrate the effectiveness of the distortion-aware beamforming approach in achieving the EE-SE tradeoff and exhibit a substantial RE performance gain over the conventional approach with ideal linear PAs assumed at the satellite transmitters.

关键词： multi-beam satellite communications nonlinear power amplifier energy and spectral efficiency tradeoff resource efficiency robust beamforming

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Cascaded four-wave mixing all-optical wavelength converter based on highly nonlinear fiber deposited graphene oxide

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Journal of Materials science & Technology 2024年第4期171卷 10-15页

作者： Yuanhongliu Gao Xiaoyu Chen Tonglei Cheng Fang Wang Xin Yan College of Information science and Engineering State Key Laboratory of Synthetical Automation for Process IndustriesNortheastern UniversityShenyang 110819China

The all-optical wavelength conversion using cascaded four-wave mixing(FWM)phenomena with graphene oxide(GO)and a highly nonlinear fiber(HNLF)device is demonstrated *** has a strong third-order nonlinear effect and is an excellent nonlinear optical material for nonlinear optical wavelength *** group velocity matching of pump and signal,HNLF,and GO amplification promote the cascaded nonlinear frequency mixing *** the experimental and analytical results,the maximum spacing between signal and pump is 21 nm,and specifically,the order of cascaded FWM light increases from order 1 to order 2 with increasing GO,and the first-order FWM conversion effi-ciency increases to a maximum of−14.5 *** the best of our knowledge,this is the first time that cascaded FWM-based all-optical wavelength conversion in HNLF-GO with wide wavelength selectivity is investigated with combined pump and signal *** findings not only provide an effective method for achieving all-optical wavelength conversion in cascaded FWM but also offer the possibility of fabricating high-performance nonlinear optical devices.

关键词： Four-wave mixing Graphene oxide Highly nonlinear fiber Optical wavelength conversion

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A guidance and control design with reduced information for a dual-spin stabilized projectile

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Defence Technology（防务技术） 2024年第3期33卷 494-505页

作者： Yu Wang Jiyan Yu Xiaoming Wang Jia Fangxiu Intelligent Ammunition Technology National Defense Key Discipline laboratory Nanjing University of Science and TechnologyNanjingJiangsu210094China

In this paper,an integrated guidance and control method based on an adaptive path-following controller is proposed to control a spin-stabilized projectile with only translational motion information under the constraint of an actuator,uncertainties in aerodynamic parameters and measurements,and control system *** to the fairly high rotation speed,the dynamic model of this missile is strongly nonlinear,uncertain and coupled in pitch,yaw and roll channels.A theoretical equivalent resultant force and uncertainty compensation method are comprehensively used to realize decoupling of pitch and *** response to the strong nonlinear and time-varying characteristics of the dynamic system,the quasi-linear model whose parameters are obtained by interpolation of points selected as the segmentation points in the trajectory envelope,is used for calculation in each *** cope with the system uncertainty caused by model approximation,parameter uncertainty and ballistic interference,an extended state estimator is used to compensate the output feedback according to the test ballistic *** order to improve the tracking efficiency and ensure the tracking error convergence with only translational motion information,the virtual guide point,whose derivative is deduced according to the Lyapunov principle,is calculated in real time according to the projection relationship between the real-time position and the reference trajectory,and a virtual line-of-sight angle and the backstepping method are used for the design of the guidance and control *** order to avoid the influence of control input saturation on the guidance and control performance due to the actuator limitation and improve the robustness of the system,an anti-saturation compensator is designed according to the two-step *** feasibility and effectiveness of the path-following controller is verified through closed-loop flight simulations with measurement,control,and condition *** result

关键词： Spin-stabilized projectile Reduced information Path-following control Extended state observer Coupled nonlinear system Input saturation

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Topological laser on square lattice with gain–loss-induced higher-order corner modes

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Chinese Physics B 2024年第6期33卷 189-195页

作者：廖明杰韦梅松王帅领许静平羊亚平 MOE Key laboratory of Advanced Micro-Structured Materials School of Physics Science and EngineeringTongji UniversityShanghai 200092China

We investigate the higher-order topological laser in the two-dimensional(2D) coupled-cavity array. By adding staggered on-site gain and loss to the 2D Hermitian array with a trivial phase, the system will emerge degenerate topological corner modes, which are protected by bulk band gap. For such a non-Hermitian model, by adjusting the parameters of the system and introducing the pumping into the cavity at the corner, a single-mode lasing with topological protection ***, single-mode lasing exists over a wide range of pumping strengths. No matter where the cavity is initially stimulated, after enough time evolution, all the cavities belonging to the topological corner mode can emit a stable laser.

关键词： topological corner modes nonlinear saturated gain single-mode lasing

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A Local Tb Theorem for Square Functions and Parabolic Layer Potentials

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Acta Mathematica Sinica,English Series 2024年第8期40卷 1941-1966页

作者： Zhi Dan WANG Guo Ming ZHANG School of Physical and Mathematical sciences Nanjing Tech UniversityNanjing 211816P.R.China Frontiers science Center for nonlinear Expectations Ministry of EductionResearch Center for Mathematics and Interdisciplinary SciencesShandong UniversityQingdao266237P.R.China

In this paper,we give a locally parabolic version of Tb theorem for a class of vector-valued operators with off-diagonal decay in L^(2) and certain quasi-orthogonality on a subspace of L^(2),in which the testing functions themselves are also *** an application,we establish the boundedness of layer potentials related to parabolic operators in divergence form,defined in the upper half-space Rn+2+:={(x,t,λ)∈R^(n+1)×(0,∞)},with uniformly complex elliptic,L^(∞),t,λ-independent coefficients,and satisfying the De Giorgi/Nash estimates.

关键词： Local Tb theorems Calderon-Littlewood-Paley family Parabolic layer potentials Carleson measure estimates

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