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Multi-layer quasi-zero-stiffness meta-structure for high-efficiency vibration isolation at low frequency

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Applied Mathematics and Mechanics(english edition) 2024年第7期45卷 1189-1208页

作者： Jiahao zhou Jiaxi zhou Hongbin PAN kai WANG Changqi CAI Guilin WeN College of Mechanical and Vehicle engineering Hunan UniversityChangsha410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body The Ministry of Science and TechnologyChangsha410082China School of Mechanical engineering Zhejiang Sci-Tech UniversityHangzhou310018China School of Mechanical engineering Yanshan UniversityQinhuangdao066004Hebei ProvinceChina

An easily stackable multi-layer quasi-zero-stiffness(ML-QZS)meta-structure is proposed to achieve highly efficient vibration isolation performance at low ***,the distributed shape optimization method is used to design the unit cel,i.e.,the single-layer QZS(SL-QZS)***,the stiffness feature of the unit cell is investigated and verified through static ***,the unit cells are stacked one by one along the direction of vibration isolation,and thus the ML-QZS meta-structure is ***,the dynamic modeling of the ML-QZS vibration isolation metastructure is conducted,and the dynamic responses are obtained from the equations of motion,and verified by finite element(Fe)***,a prototype of the ML-QZS vibration isolation meta-structure is fabricated by additive manufacturing,and the vibration isolation performance is evaluated *** results show that the vibration isolation performance substantially enhances when the number of unit cells *** importantly,the ML-QZS meta-structure can be easily extended in the direction of vibration isolation when the unit cells are properly ***,the ML-FQZS vibration isolation meta-structure should be a fascinating solution for highly efficient vibration isolation performance at low frequency.

关键词： quasi-zero stiffness(QZS) meta-structure high efficiency low frequency vibration isolation

Prescribed-time leader-following consensus of linear multi-agent systems by bounded linear time-varying protocols

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Science China(Information Sciences) 2024年第1期67卷 140-153页

作者： kai ZHANG Bin zhou Xuefei YANG Guangren DUAN Center for Control Theory and Guidance Technology Harbin Institute of Technology

This paper considers the prescribed-time leader-following consensus problem of input-constrained linear multi-agent systems under generally directed communication topology in two cases:the Laplacian matrix related to the entire communication topology between agents is either known or *** particular,the consensus problem for the former case is solved by a novel bounded linear time-varying(LTV) protocol,where the feedback gain is formulated by the parametric Lyapunov equation and the knowledge of the Laplacian ***,by utilizing a distributed observer,a fully bounded LTV protocol is proposed for the latter *** should be noted that,compared with the existing results,the system under consideration is more general,the designed protocols are linear,and the consensus problem is accomplished even in a fully distributed ***,the effectiveness of the proposed approach is verified by a numerical example.

关键词： leader-following consensus time-vary feedback prescribed-time control fully distributed consensus

Convex-up Style of Deformation within Grabens in Regions of Incomplete Crossing Conjugate Normal Faults: A Numerical Simulation Investigation and Case Study

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Journal of earth Science 2024年第3期35卷 839-849页

作者： Zheng Li kai Wang Xiong Xiong Bing zhou School of Geophysics and Geomatics China University of GeosciencesWuhan 430074China State Key Laboratory of Geodesy and earth’s Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430077China Department of earth Sicences Khalifa UniversityAbu DhabiUnited Arab Emirates

Crossing conjugate normal faults(CCNFs)are extensively developed in many hydrocarbon-producing basins,generally existing in the form of incomplete ***,the effect of the non-conjugate zone of the CCNFs on the conjugate relay zone post late tectonic action has not been previously *** use 3D elastic-plastic modeling to investigate the influence of incomplete(i.e.,partially intersecting)CCNFs on the pattern of deformation of strata in the intersection region.A series of model simulations were performed to examine the effects of horizontal tectonic extension,fault size,and fault depth on the deformation of conjugate relay zones of incomplete *** analyses yielded the following results.(1)The model of incomplete conjugation predicts a convex-up style of deformation in the conjugate graben region superimposed on overall subsidence under applied horizontal tectonic extension.(2)The degree of convex-up deformation of the conjugate graben depends on the influence of the non-conjugate zone on the conjugate relay zone,which varies with the amount of horizontal tectonic extension,fault size,and fault burial depth.(3)Our results indicate that incomplete CCNFs can form convex-up deformation,similar to that in the Nanpu Sag area and provide a sound understanding of hydrocarbon migration and accumulation.

关键词： incomplete conjugate normal fault conjugate graben convex-up deformation hydrocarbons Nanpu Sag tectonics.

Spherical Confinement Generates entropic Force to Accelerate Polymer Chain Detachment

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Chinese Journal of Polymer Science 2024年第3期42卷 407-416,I0010页

作者： Yu-Shan Zheng Jian-Ping zhou Yan Xu kai Li Mechanical engineering Xinjiang UniversityUrumqi 830002China

To understand the dynamic process of polymer detachment, it is necessary to determine the mean detachment time of a single breakable link, which is modeled as a spring. Normally, this time can be viewed as the escape of a Brownian particle from the potential well of the spring. However, as the free dangling length of the polymer chain increases, the conformational entropy of the chain is affected by geometric confinement. It means that the wall exerts a repulsive force on the chain, resulting in accelerated link detachment from a macroscopic perspective. In this work, we investigate the effect of entropy on the detachment rate in the case where the substrate is spherical. We demonstrate that spherical confinement accelerates chain detachment both inside and outside the sphere. An analytical expression for the mean detachment time of breakable links is given, which includes an additional pre-factor that is related to the partition function. Additionally, we analyze the expressions for entropic forces inside the sphere, outside the sphere, and on a flat wall, comparing their magnitudes to explain the difference in mean detachment time.

关键词： Polymer detachment Breakable link entropic force Mean first passage time

Online estimation and characteristic analysis of double nugget diameters during aluminum/steel resistance spot welding process

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Journal of Iron and Steel Research International 2024年第8期31卷 2053-2067页

作者： Kang zhou Wen-xiao Yu Bao-kai Ren Gang Wang School of Mechatronical engineering Beijing Institute of TechnologyBeijing 100081China

Online estimation of the double nugget diameters was performed by means of a back propagation neural *** double nugget diameters were obtained using actual welding experiment and numerical simulation,according to different characteristics of aluminum nugget and steel *** input of the neural network was some key characteristic parameters extracted from dynamic power signal,which were peak point,knee point and their variation rate over time,as well as heat energy delivered into the welding *** architecture of the neural network was confirmed by confirming the number of neurons in hidden layer through a series of *** key parameters of the neural network were obtained by means of training 81 arrays of data ***,the neural network was used to test the remaining 20 arrays of verifying data set,and the results showed that both of the mean errors for the two nugget diameters were below 3%.In addition,corresponding analyses showed that the accuracy of two nugget diameters was higher than that of tensile-shear strength.

关键词： Resistance spot welding Aluminum Steel Double nugget Dynamic power signal.Neural network

Multiplexed manipulation of orbital angular momentum and wavelength in metasurfaces based on arbitrary complex-amplitude control

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Light(Science & Applications) 2024年第5期13卷 930-940页

作者： Guoli He Yaqin Zheng Changda zhou Siyang Li Zhonghong Shi Yanhui Deng Zhang-kai zhou State Key Laboratory of Optoelectronic Materials and Technologies School of PhysicsSun Yat-sen UniversityGuangzhou 510275China

Due to its unbounded and orthogonal modes,the orbital angular momentum(OAM)is regarded as a key optical degree of freedom(DoF)for future information processing with ultra-high capacity and *** the manipulation of OAM based on metasurfaces has brought about great achievements in various fields,such manipulation currently remains at single-DoF level,which means the multiplexed manipulation of OAM with other optical DoFs is still lacking,greatly hampering the application of OAM beams and advancement of *** order to overcome this challenge,we propose the idea of multiplexed coherent pixel(MCP)for *** approach enables the manipulation of arbitrary complex-amplitude under incident lights of both plane and OAM waves,on the basis of which we have realized the multiplexed DoF control of OAM and *** a result,the MCP method expands the types of incident lights which can be simultaneously responded by metasurfaces,enriches the information processing capability of metasurfaces,and creates applications of information encryption and OAM *** findings not only provide means for the design of high-security and high-capacity metasurfaces,but also raise the control and application level of OAM,offering great potential for multifunctional nanophotonic devices in the future.

关键词： momentum offering overcome

Predicting Rock Burst in Underground engineering Leveraging a Novel Metaheuristic-Based LightGBM Model

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Computer Modeling in engineering & Sciences 2024年第7期140卷 229-253页

作者： kai Wang Biao He Pijush Samui Jian zhou No.Three engineering Co. Ltd.CCCC First Highway Engineering CompanyBeijing101102China Department of Civil engineering Faculty of EngineeringUniversiti MalayaKuala Lumpur50603Malaysia Department of Civil engineering National Institute of Technology PatnaBihar800005India School of Resources and Safety engineering Central South UniversityChangsha410083China

Rock bursts represent a formidable challenge in underground engineering,posing substantial risks to both infrastructure and human *** sudden and violent failures of rock masses are characterized by the rapid release of accumulated stress within the rock,leading to severe seismic events and structural ***,the development of reliable prediction models for rock bursts is paramount to mitigating these *** study aims to propose a tree-based model—a Light Gradient Boosting Machine(LightGBM)—to predict the intensity of rock bursts in underground engineering.322 actual rock burst cases are collected to constitute an exhaustive rock burst dataset,which serves to train the *** population-basedmetaheuristic algorithms are used to optimize the hyperparameters of the LightGBM ***,the sensitivity analysis is used to identify the predominant factors that may incur the occurrence of rock *** results show that the population-based metaheuristic algorithms have a good ability to search out the optimal hyperparameters of the LightGBM *** developed LightGBM model yields promising performance in predicting the intensity of rock bursts,with which accuracy on training and testing sets are 0.972 and 0.944,*** sensitivity analysis discloses that the risk of occurring rock burst is significantly sensitive to three factors:uniaxial compressive strength(σc),stress concentration factor(SCF),and elastic strain energy index(Wet).Moreover,this study clarifies the particular impact of these three factors on the intensity of rock bursts through the partial dependence plot.

关键词： Rock burst prediction LightGBM coati optimization algorithm pelican optimization algorithm partial dependence plot

effects of hot deformation and in-situ ZrB2 particle on microstructure and tensile performance of AA7085 composite sheets

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Journal of Iron and Steel Research International 2024年第7期31卷 1778-1791页

作者： Jiang-jing Wu Xi-zhou kai Chuang Guan Yu-tao Zhao School of Material Science and engineering Jiangsu UniversityZhenjiang 212013JiangsuChina

To provide a new idea to reduce anisotropy for sheets in the thickness direction by microstructure modification and,mean-while,maintain or even enhance tensile performance,the in-situ ZrB2 particle/AA7085 composite sheets with thicknesses of 1,2,3,and 6 mm were *** as-cast grain size was significantly refined by the heterogeneous nucleus of the ZrB2 *** microstructure results show that severe hot deformation converts as-cast disordered microstructure into a sequential microstructure by crushing the remanent phases and matrix into a fiber *** the solid solution and aging heat treatment,the composite sheets exhibit largely recrystallized grains compared with partially recrystallized grains in the matrix sheets,and weak or even free texture exists in the *** grain size in the composite sheets decreases with the increase in thickness *** the thickness range of 1-3 mm,the composite sheets maintain a similar tensile per-formance as that in matrix sheets,while the strength and ductility in the 6-mm-thick composite sheet are improved.

关键词： Composite sheet Grain structure Texture Dislocation Strengthening

Design of quasi-zero-stiffness elastic diodes for low-frequency nonreciprocity through machine learning

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Acta Mechanica Sinica 2024年第7期40卷 137-151页

作者： Junsen He Jiaxi zhou kai Wang Qiang Wang College of Mechanical and Vehicle engineering Hunan UniversityChangsha 410082China Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan UniversityChangsha 410082China Department of Mechanical engineering Hong Kong Polytechnic UniversityHong KongChina

elastic diodes with nonreciprocity have the potential to enable unidirectional modulation of elastic ***,it is a challenge to achieve nonreciprocity at low frequencies(<100 Hz)using existing elastic *** paper proposes... 详细信息

elastic diodes with nonreciprocity have the potential to enable unidirectional modulation of elastic ***,it is a challenge to achieve nonreciprocity at low frequencies(existing elastic *** paper proposes a quasizero-stiffness(QZS)elastic diode to resolve such a tough issue and fulfill high-quality low-frequency *** proposed elastic diode is invented by combining a QZS locally resonant metamaterial with a linear one,where the beneficial nonlinearity of the QZS metamaterial facilitates opening an amplitude-dependent band gap at very low ***,the dispersion relation of the QZS metamaterial is derived theoretically based on the harmonic balance method(HBM).Then,the transmissibility of the QZS elastic diode in both the forward and backward directions is calculated through theoretical analyses and numerical ***,the influences of system parameters on the low-frequency nonreciprocal effect are *** results indicate that considerable nonreciprocity is observed at a quite low frequency(e.g.,9 Hz),which is achieved by amplitude-dependent local resonance combined with interface ***,a machine learning-based design optimization is introduced to evaluate and enhance the nonreciprocal effect of the QZS elastic *** the aid of machine learning(ML),the computational cost of predicting nonreciprocal effects during design optimization can be significantly *** design optimization,the nonreciprocal frequency bandwidth can be broadened while maintaining considerable isolation quality at low frequencies.

关键词： Nonreciprocity Low-frequency elastic diode Quasi-zero-stiffness Nonlinear elastic metamaterials Machine learning