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Holder continuous weak solutions of the 2D Boussinesq equation with thermal diffusion

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Sc.ence china Mathematics 2024年第8期67卷 1777-1806页

作者： Tianwen Luo tao tao Liqun Zhang Yau Mathematical Sc.ences center Tsinghua UniversityBeijing 100084China School of Mathematics Shandong UniversityJinan 250100China Institute of Mathematics Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sc.ences University of Chinese Academy of SciencesBeijing 100049China

We show the existence of Holder continuous periodic weak solutions of the 2D Boussinesq equation with thermal diffusion which satisfy the prescribed kinetic *** precisely,for any smooth e(t):[0,1]→R+andε∈(0,110),there exist v∈c 110−ε([0,1]×T2)andθ∈c 1,120−εt 2 c 2,1 x 10−ε([0,1]×T2),which satisfy(1.1)in the sense of distribution and e(t)=ˆT2|v(t,x)|2 dx,∀t∈[0,1].

关键词： 2D Boussinesq equation with thermal diffusion Holder continuous periodic weak solutions prescribed kinetic.energy

Modelling the brittle rock failure by the quaternion-based bonded-partic.e model in DeM

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Rock Mechanics Bulletin

Rock Mechanics Bulletin 2024年第2期3卷 87-95页

作者： tao Zhao Philip e.F.collins Department of civil and environmental engineering Brunel University LondonLondonUB83PHUnited Kingdom

This paper presents an investigation of brittle rock failure by the quaternion-based bonded-partic.e model in disc.ete element method(DeM).Unlike traditional approac.es that utilize euler angles or rotation matrices,this model employs unit quaternions to represent the spatial rotations of *** method simplifies the rep-resentation of 3D rotations,providing a more intuitive framework for modelling complex interactions in granular *** numerical model was validated by the uniaxial compression tests on rock,with good agreement with well-documented experimental data in terms of the rock uniaxial compression strength(UcS)and failure *** loading,the rock sample demonstrated a linear-elastic response at an axial strain of smaller than 0.45%.However,as internal bond breakage accumulated,this linear relationship weakened,and the stress-strain curve began to deviate from its initial linear *** bond breakage and the overall deformation of the rock were primarily controlled by the shear bonding *** UcS was achieved at an axial strain of 0.625%,at which point the internal shear bonding force chains were predominantly aligned *** brittle failure occurred when the internal damage of solids nuc.eated to form an interconnec.ed failure plane,accompanied by a sharp rise in the internal damage *** area of failure plane inc.eased with the loading strain rate,gradually transforming the failure pattern from the local damage to a complete fragmentation.

关键词： Brittle failure Quaternion DeM bonded model Uniaxial compression test Rate dependent Internal damage

Finite barrier bound state

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Light(Sc.ence & Applications) 2024年第4期13卷 664-671页

作者： tao Liu Kai Bai Yic.eng Zhang Duanduan Wan Yun Lai c.T.chan Meng Xiao Key Laboratory of Artificial Micro-and Nano-structures of Ministry of education and School of Physics and Technology Wuhan University430072 WuhanChina. National Laboratory of Solid State Microstructures School of Physicsand Collaborative Innovation Center of Advanced MicrostructuresNanjing University210093 NanjingChina. Department of Physics The Hong Kong University of Science and TechnologyClear Water BayKowloon999077Hong KongChina. Wuhan Institute of Quantum Technology 430206 WuhanChina

A boundary mode localized on one side of a finite-size lattice can tunnel to the opposite side which results in unwanted *** wisdom tells that the tunneling probability decays exponentially with the size of the system which thus requires many lattice sites before eventually becoming negligibly *** we show that the tunneling probability for some boundary modes can apparently vanish at specific ***,similar to bound states in the continuum,a boundary mode can be completely trapped within very few lattice sites where the bulk bandgap is not even *** intriguingly,the number of trapped states equals the number of lattice sites along the normal direction of the *** provide two configurations and validate the existence of this peculiar finite barrier-bound state experimentally in a dielectric photonic crystal at microwave *** work offers extreme flexibility in tuning the coupling between localized states and channels as well as a new mechanism that facilitates unprecedented manipulation of light.

关键词： boundary state eventually

Brain-inspired chaotic spiking backpropagation

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National Sc.ence Review 2024年第6期11卷 169-179页

作者： Zijian Wang Peng tao Luonan c.en Key Laboratory of Systems Health Sc.ence of Zhejiang Province School of Life ScienceHangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences Key Laboratory of Systems Biology Shanghai Institute of Biochemistry and Cell Biology Center for Excellence in Molecular Cell Science Chinese Academy of Sciences Guangdong Institute of Intelligence Sc.ence and Technology Pazhou Laboratory(Huangpu)

Spiking neural networks(SNNs) have superior energy effic.ency due to their spiking signal transmission,which mimics biological nervous systems, but they are difficult to train effectively. Although surrogate gradient-based methods offer a workable solution, trained SNNs frequently fall into local minima because they are still primarily based on gradient dynamics. Inspired by the chaotic dynamics in animal brain learning, we propose a chaotic spiking backpropagation(cSBP) method that introduces a loss function to generate brain-like chaotic dynamics and further takes advantage of the ergodic and pseudo-random nature to make SNN learning effective and robust. From a computational viewpoint, we found that cSBP significantly outperforms current state-of-the-art methods on both neuromorphic data sets(***-cIFAR10 and DVS-Gesture) and large-scale static data sets(e.g. cIFAR100 and Image Net) in terms of accuracy and robustness. From a theoretical viewpoint, we show that the learning process of cSBP is initially chaotic, then subject to various bifurcations and eventually converges to gradient dynamics,consistently with the observation of animal brain activity. Our work provides a superior core tool for direct SNN training and offers new insights into understanding the learning process of a biological brain.

关键词： spiking neural networks surrogate gradient local minima backpropagation brain-inspired learning chaos

A review of microwave-metal discharge interaction:Mechanism,regulation,and application for synthesis of nanomaterials

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Nano Research 2024年第10期17卷 9225-9254页

作者： Yixuan Xie Ruiqian Shi Benwei Fu c.engyi Song Wen Shang Peng tao tao Deng State Key Laboratory of Metal Matrix composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China National engineering Research center of Special equipment and Power System for Ship and Marine engineering Shanghai 200030China

Placing metals within microwave ovens has been generally viewed as a dangerous practice because of occurrence of violent discharge,but in recent years such discharge phenomenon has attrac.ed inc.easing attention and has enabled a variety of exciting *** this work,we provide a comprehensive review of fundamental understanding of microwave-metal discharge interaction and its state-of-the-art application for nanomaterials *** introduce the microscopic interaction between different categories of materials and the electric and magnetic field of *** microwave-metal interaction,we highlight its size-dependence and point out the influence of the oxide layer on the surface of *** discuss the required conditions for occurrence of discharge,microscopic formation mechanism,and charac.eristic features of microwave-metal discharge *** analyzing the influence from the microwave input,discharging metals,and surrounding discharging media,we discuss the strategy for systematical regulation of the discharge *** describe the applications of the microwave-metal discharge for facile synthesis of various functional nanomaterials including core-shell carbon/metal,metal oxides,metal chalcogenides,intermetallic compounds,metallic nanopartic.es and metallic compounds,and organic ***,the challenges in precise charac.erization and dynamic regulation of the discharge process as well as exciting application opportunities are discussed.

关键词： microwave-metal interaction discharge microwave heating skin depth nanomaterial synthesis

camera,LiDAR,and IMU Based Multi-Sensor Fusion SLAM:A Survey

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Tsinghua Sc.ence and Technology 2024年第2期29卷 415-429页

作者： Jun Zhu Hongyi Li tao Zhang Department of Automation Tsinghua UniversityBeijing 100084China

In recent years,Simultaneous Localization And Mapping(SLAM)technology has prevailed in a wide range of applications,such as autonomous driving,intelligent robots,Augmented Reality(AR),and Virtual Reality(VR).Multi-sensor fusion using the most popular three types of sensors(e.g.,visual sensor,LiDAR sensor,and IMU)is becoming ubiquitous in SLAM,in part because of the complementary sensing capabilities and the inevitable shortages(e.g.,low precision and long-term drift)of the stand-alone sensor in challenging *** this artic.e,we survey thoroughly the research efforts taken in this field and strive to provide a concise but complete review of the related ***,a brief introduction of the state estimator formation in SLAM is ***,the state-of-the-art algorithms of different multi-sensor fusion algorithms are *** we analyze the defic.enc.es associated with the reviewed approac.es and formulate some future research *** paper can be considered as a brief guide to newcomers and a comprehensive reference for experienced researc.ers and engineers to explore new interesting orientations.

关键词： multi-sensor fusion Simultaneous Localization And Mapping(SLAM) navigation localization

Mixed Alkali-zinc.effects on Thermo-mechanical Properties in Borosilicate Glasses

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Journal of Wuhan University of Technology(Materials Sc.ence) 2024年第5期39卷 1093-1099页

作者： XIAO Guanzhou tao Yunhang ZHOU Hemin ZHeNG Qingshuang QIAO Ang tao Haizheng State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China Wuhan University of Technology Advanced engineering Technology Research Institute of Zhongshan city Zhongshan 528437China

A series of mixed alkali-zinc borosilicate glasses with various r values(r=molar ratio of[ZnO]/([R^(2)O]+[ZnO]))from 0.00 to 1.00 were fabricated to probe the mixed alkali-zinc.effects on thermo-mechanical *** nonlinear evolution of glass transition temperature(T_(g))with the addition of ZnO is ascribed to the competition of two converse factors,i e,the T_(g)depression as one of the colligative properties for a solution,on the one hand,and the enhancement of T_(g)due to the higher field strength of zinc cations compared to that of alkali ***,the nonlinear evolution of elastic moduli and c.effic.ents of thermal expansion with r is attributed to the variance of intermediate-range clusters,which is confirmed by infrared and Raman scattering *** findings are very helpful in tailoring the performance of borosilicate glasses.

关键词： glass transition temperature elastic moduli c.effic.ent of thermal expansion borosilicate glass

Hybrid 3D printed three-axis force sensor aided by machine learning decoupling

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International Journal of Smart and Nano Materials 2024年第2期15卷 261-278页

作者： Guotao Liu Peishi Yu Yin tao tao Liu Hezun Liu Junhua Zhao Jiangnan Key Laboratory of Advanced Food Manufacturing equipment and Technology School of Mechanical EngineeringJiangnan UniversityWuxiPR China Jiangsu Province engineering Research center of Micro-Nano Additive and Subtractive Manufacturing Institute of Advanced TechnologyJiangnan UniversityWuxiPR China

Identification of magnitude and orientation for spatially applied loading is highly desired in the fields of not only the machinery components but also human-machine *** the fact that the 3-axis force sensor with different structures has been proposed to measure the spatial force,there are still some common limitations including the multi-step manufacturing-assembly processes and complicated testing of decoupling ***,we propose a rapid fabrication strategy with low-cost to achieve high-precision 3-axis force *** sensor is designed to compose of structural Maltese cross base and sensing *** is directly fabricated within one step by a hybrid 3D printing technology combining deposition modeling(FDM)with direct-ink-writing(DIW).In particular,a machine learning(ML)model is used to convert the strain signal to the force *** of a mount of calibration tests,this ML model is trained by suffic.ent simulation data based on programmed batch finite element *** sensor is capable of continuously identifying a spatial force with varying magnitude and orientation,which suc.essfully quantify the applied force of traditional chinese medicine physiotherapy including Gua Sha and *** work provides insight for design and rapid fabrication of multi-axis force sensors,as well as potential applications.

关键词： Hybrid 3D printing 3-axis force sensor machine learning nonlinear decoupling

Mechanical behavior and damage constitutive model of sandstone under hydro-mechanical (H-M) coupling

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International Journal of Mining Sc.ence and Technology 2024年第6期34卷 837-853页

作者： tao Tan chunyang Zhang Yanlin Zhao Xiaoshuang Li School of Resources and environmental engineering Wuhan University of TechnologyWuhan 430070China State Key Laboratory of Safety and Health in Metal Mines Maanshan 243000China Sinosteel Maanshan General Institute of Mining Research co. Ltd.Maanshan 243000China School of Resource&environment and Safety engineering Hunan University of Science and TechnologyXiangtan 411201China School of Urban construction Changzhou UniversityChangzhouJiangsu 213164China

Underground engineering often passes through water-rich fractured rock masses, which are prone to fracture and instability under the long-term coupling of in-situ stress field and pore water(P-W) pressure, ultimately threatening the stability of underground structures. In order to explore the mechanical properties of rocks under H-M coupling, the corresponding damage constitutive(D-c) model has become the focus of attention. considering the inadequacy of the current research on rock strength parameters,energy evolution charac.eristics and D-c model under H-M coupling, the mechanical properties of typical sandstone samples are discussed based on laboratory tests. The results show that the variation of charac.eristic stresses of sandstone under H-M coupling conforms to the normalized attenuation equation and Mohr-coulomb(M-c) criterion. The P-W pressure mechanism of sandstone exhibits a dynamic change from softening effect to H-M fracturing effect. The closure stress is mainly provided by cohesive strength, while the initiation stress, damage stress, and peak stress are jointly dominated by cohesive strength and friction strength. In addition, residual stress is attributed to the friction strength formed by the bite of the fracture surface. Subsequently, the energy evolution charac.eristics of sandstone under H-M coupling were studied, and it was found that P-W pressure weakened the energy storage capacity and energy dissipation capacity of sandstone, and H-M fracturing was an important factor in reducing its energy storage effic.ency. Finally, combined with energy dissipation theory and statistical damage theory, two types of D-c models considering P-W pressure are proposed accordingly, and the model parameters can be determined by four methods. The application results indicate that the proposed and modified D-c models have high reliability, and can charac.erize the mechanical behavior of sandstone under H-M coupling, overcome the inconvenience of existing D-c models

关键词： H-M coupling Water-saturated sandstone Mechanical mechanism energy evolution D-c model