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Effects of bidirectional interaction on inelastic seismic response:When is its effect significant?

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Earthquake Engineering and Engineering Vibration 2025年第1期24卷 113-134页

作者： Atanu Santra Rana Roy Department of Aerospace Engineering and applied mechanics Indian Institute of Engineering Science and TechnologyShibpur 711103India

Motivated by the early works on bidirectional interaction and the breakthrough to estimate seismic response to bidirectional shaking via unidirectional analysis,it is essential to answer the question:When is the interaction effect significant?Early works concluded that the effect of interaction is pronounced for stiff systems;consequently,the straightforward method for estimating seismic response to bidirectional excitation by using unidirectional analyses is verified primarily for short period ***,it is essential to identify the domain of significance for bidirectional interaction before adopting this simple methodology in *** parametrically defined systems with elastoplastic and degrading hysteresis models are studied under near-fault motions,assuming strength-independent and strength-dependent *** force-based and displacement-based analyses,conducted in parallel,reveal that the interaction effect is considerable for stiff systems,especially with degrading characteristics in a relatively low inelasticity ***,the bidirectional effect may be significant even for highly flexible systems,especially for residual deformation,which in earlier works was *** range of significance depends on the hysteresis model,system parameters,and response *** analysis is carried out with the results of the case studies,and the derived regression models may be used for a preliminary assessment of the impact of interaction in advance.

关键词： bidirectional residual forward-directive fling force-based displacement-based regression

A quantum-search-based multi-classifier for image recognition

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Science China(Physics,mechanics & Astronomy) 2025年第1期68卷 17-27页

作者： Lu Liu Xingyu Wu Lufan Zhang Chuan Wang School of Artificial Intelligence Beijing Normal UniversityBeijing 100875China applied Optics Beijing Area major Laboratory Beijing Normal UniversityBeijing 100875China

The multi-class classification of images is a pivotal challenge within the realm of image *** the volume of visual data continues to expand,there is a burgeoning interest in harnessing the unique capabilities of quantum computation to augment the efficiency of classification ***,many existing methods for training quantum image multi-classifiers parallel classical machine learning techniques,where the requisite circuit measurements increase linearly with the volume of training *** work introduces a novel approach for training a quantum image multi-classifier based on the quantum search *** have meticulously conducted rigorous experiments on a handwritten digit dataset,a classic benchmark in the *** results have been meticulously compared with previous works,and the comparative analysis not only validates the efficiency of our proposed approach,requiring only O(N/b)measurements during training,but also highlights a significant quadratic speedup of the algorithm.

关键词： quantum computation image recognition quantum search algorithm

Disentangling electronic and phononic thermal transport across two-dimensional interfaces

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Chinese Physics B 2025年第2期34卷 401-406页

作者： Linxin Zhai Zhiping Xu applied mechanics Laboratory Department of Engineering MechanicsTsinghua UniversityBeijing 100084China

Electrical and thermal transport at two-dimensional(2D) interfaces is critical for semiconductor technology, yet their interplay remains unclear. We report a theoretical proposal to separate electronic and phononic contributions to thermal conductance at 2D interfaces with graphene, which is validated by non-equilibrium Green's function calculations and molecular dynamics simulations for graphene–gold contacts. Our results reveal that while metal–graphene interfaces are transparent for both electrons and phonons, non-covalent graphene interfaces block electronic tunneling beyond two layers but not phonon transport. This suggests that the Wiedemann–Franz law can be experimentally tested by measuring transport across interfaces with varying graphene layers.

关键词： electrical and thermal transport 2D interfaces Wiedemann–Franz law theoretical proposal

Tunable non-Markovian and quantum coherence in the single-qubit dephasing noise channel

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Science China(Physics,mechanics & Astronomy) 2025年第3期68卷 92-101页

作者： Na-Na Zhang Chao-Yi Wu Xu Zhou Qi-Yuan Liu Cheng-Ge Liu Yong-Rui Guo Ren-Pu Li School of Optoelectronic Engineering Chongqing University of Posts and TelecommunicationsChongqing400065China Department of Physics Applied Optics Beijing Area Major LaboratoryBeijing Normal UniversityBeijing100875China

In this paper,we construct a single-qubit dephasing noise channel based on the nuclear magnetic resonance(NMR)system by employing the bath-engineering technology,and achieve the construction of the tunable non-Markovian environment in the dephasing noise *** findings indicate that for the single-qubit system,the transition of system dynamics from Markovian to non-Markovian can be achieved by adjusting the base frequency of the noise power ***,the base frequency corresponding to this phase transition point is not fixed,and there is a certain relationship between it and the total evolution time of the single-qubit *** our research,we discovered a fundamental relationship:if the single-qubit system dynamics undergoe a transition from Markovian to non-Markovian atω_(0) within 0-2t ms,shortening the evolution time to 0-t ms results in an increase of the phase transition point to 2ω_(0).This insight offers crucial guidance for artificially crafting non-Markovian environments across arbitrary time scales in single-qubit systems,and it is not limited by the type of *** from system dynamics,quantum coherence is also a focal point of our *** find that when the system dynamics exhibit non-Markovian behavior,the quantum coherence of the single-qubit system experiences ***,the timing of these coherence revivals aligns with the instants of the non-Markovianity ***,our research also serves as a pivotal foundation for the artificial manipulation and realization of quantum coherence revivals within diverse single-qubit systems.

关键词： dephasing noise channel non-Markovian quantum coherence

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Some fundamental issues in buoyancy-driven flows with implications for geophysical and astrophysical systems

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Acta Mechanica Sinica 2025年第1期41卷 1-21页

作者： Ke-Qing Xia Kai Leong Chong Guang-Yu Ding Lu Zhang Center for Complex Flows and Soft Matter Research Southern University of Science and TechnologyShenzhen 518055China Department of mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen 518055China Shanghai Key Laboratory of mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China

Buoyancy-driven flows are prevalent in a wide range of geophysical and astrophysical systems. In this review, we focus on threepivotal effects that significantly influence the dynamics and transport properties of buoyancy-driven flows and may have impli-cations for natural systems. These effects pertain to the role of boundary conditions, the impact of rotation, and the effect offinite size. Boundary conditions represent how the fluid flow interacts with different kinds of surfaces. Rotation, as the Earth’srotation in geophysical systems or the whirling of astrophysical systems, introduces Coriolis and centrifugal forces, leading tothe profound vortical structure and distinct transport property. Finite size, representing geometrical constraints, influences thebehavior of buoyancy-driven flows across varying geometrical settings. This review aims to provide a holistic understanding ofthe intricate interplay of these factors, offering insights into the complex natural phenomena from the perspectives of the threeeffects.

关键词： Buoyancy-driven flows Geophysical turbulence Rayleigh-B´enard convection

Machine learning-encoded multiscale modelling and Bayesian optimization framework to design programmable metamaterials

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Acta Mechanica Sinica 2025年第1期41卷 226-245页

作者： Yizhe Liu Xiaoyan Li Yuli Chen Bin Ding National Key Laboratory of Strength and Structural Integrity Institute of Solid MechanicsBeihang University(BUAA)Beijing 100191China Centre for Advanced mechanics and Materials Applied Mechanics LaboratoryDepartment of Engineering MechanicsTsinghua UniversityBeijing 100084China

Advanced programmable metamaterials with heterogeneous microstructures have become increasingly prevalent in scientific and engineering disciplines attributed to their tunable ***,exploring the structure-property relationship in these materials,including forward prediction and inverse design,presents substantial *** inhomogeneous microstructures significantly complicate traditional analytical or simulation-based ***,we establish a novel framework that integrates the machine learning(ML)-encoded multiscale computational method for forward prediction and Bayesian optimization for inverse *** prior end-to-end ML methods limited to specific problems,our framework is both load-independent and *** means that a single training session for a constitutive model suffices to tackle various problems directly,eliminating the need for repeated data collection or *** demonstrate the efficacy and efficiency of this framework using metamaterials with designable elliptical holes or lattice honeycombs *** accelerated forward prediction,we can precisely customize the stiffness and shape of metamaterials under diverse loading scenarios,and extend this capability to multi-objective customization ***,we achieve topology optimization for stress alleviation at the crack tip,resulting in a significant reduction of Mises stress by up to 41.2%and yielding a theoretical interpretable *** framework offers a general,efficient and precise tool for analyzing the structure-property relationships of novel metamaterials.

关键词： Artificial neural network Multiscale computation Bayesian optimization Inverse design Programmable metamaterials

Toward Analytical Homogenized Relaxation Modulus for Fibrous Composite Material with Reduced Order Homogenization Method

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Computers, Materials & Continua 2025年第1期82卷 193-222页

作者： Huilin Jia Shanqiao Huang Zifeng Yuan HEDPS Center for Applied Physics and Technology(CAPT)Department of Mechanics and Engineering SciencePeking UniversityBeijing100871China State Key Laboratory for Turbulence and Complex Systems Peking UniversityBeijing100871China

In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational *** method is based on the reduced-order homogenization(ROH)*** ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization *** to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained *** the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive *** method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical *** approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading *** sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic ***,the model is validated against experimental measurements,confirming its accuracy and reliability.

关键词： Homogenized relaxation modulus viscoelastic standard solid model reduced order homogenization fibrous composite material

Targets capture by distributed active swarms via bio-inspired reinforcement learning

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Science China(Physics,mechanics & Astronomy) 2025年第1期68卷 206-217页

作者： Kun Xu Yue Li Jun Sun Shuyuan Du Xinpeng Di Yuguang Yang Bo Li Institute of Biomechanics and Medical Engineering Applied Mechanics LaboratoryDepartment of Engineering MechanicsTsinghua UniversityBeijing 100084China Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084China Shanghai Aerospace Control Technology Institute Shanghai 201109China Shanghai Key Laboratory of Aerospace Intelligent Control Technology Shanghai 201109China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Natural swarms arranged from cells to herds are usually decentralized but display intriguing collective intelligence in coordinating individuals across large scales to efficiently achieve their common *** from nature may provide new strategies for controlling collective dynamics of synthetic swarms to accomplish specific ***,we present a bioinspired computational framework that steers distributed active swarms to collectively capture and merge targets via reinforcement *** exploit collective milling structures of natural herds to cage the targets,and adopt a switching control policy inspired by sperms’chiral dynamics to optimize the trajectories of individuals,through which the active swarms can selforganize to enclose single or multiple distant targets in a dynamical,adaptive and scalable *** exists a critical swarm size,beyond which the excessive competition between agents would generate large mechanical forces,leading to capture instability but enabling the transition from short-distance to long-distance merging capture of multiple *** work provides physical insights into distributed active swarms and could offer a multilevel,decentralized strategy toward controlling swarm robotics in wide applications such as bio-medical devices,machine immunity,and target clearance.

关键词： swarm intelligence robotics multi-tasks artificial intelligence bionics

Cyclic loading of marble:Correlating the attenuation of the electric and acoustic activities and highlighting criticality indices in terms of natural time

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International Journal of Mining Science and Technology 2025年第2期35卷 159-174页

作者： Dimos Triantis Ilias Stavrakas Ermioni D.Pasiou Stavros K.Kourkoulis University of West Attica Department of Electrical&Electronics EngineeringElectronic Devices and Materials LaboratoryAncient Olive Grove CampusAthens 12244Greece National Technical University of Athens School of Applied Mathematical and Physical SciencesDepartment of MechanicsLaboratory for Testing and MaterialsAthens 15773Greece

The attenuation of the acoustic activity in marble specimens under uniaxial compressive loadingunloading loops is quantified in juxtaposition to that of the electric *** parallel,the existence of"pre-failure indiceso"warning about entrance into a critical stage,that of impending fracture,is *** acoustic activity is quantified in terms of the normalized number of acoustic hits,their average rate of production and their cumulative energy,and,the cumulative counts and their average rate of *** electric activity is studied in terms of the pressure stimulated currents and the electric charge *** analysis revealed that the acoustic and electric activities are linearly correlated to each other,suggesting that they are different manifestations of the same damage *** addition,Kaiser's effect,governing the acoustic activity,is found to govern,also,the electric ***,it is concluded that entrance into the critical stage is safely predicted by means of a simple criterion,based on the evolution of the average rate of change of the normalized cumulative counts in the natural time *** predictions are almost identical with those of the criterion based on the "varianceo" and the "entropies" of the time series of acoustic events in this domain.

关键词： Marble cyclic loading Acoustic emissions Kaiser's effect Pressure stimulated currents Criticality indices Natural time