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SSRN 2024年

作者： Zhang, Jianjun Dang, Xiangxin Wang, Jianxiang Lu, Guoxing School of Engineering Swinburne University of Technology HawthornVIC3122 Australia State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering Science College of Engineering Peking University Beijing100871 China CAPT-HEDPS IFSA Collaborative Innovation Center of MoE College of Engineering Peking University Beijing100871 China

Tube is a common structural component for energy absorption and structural protection against impact in engineering. Origami has emerged as a method to improve the performance of pre-folded tubes in this regard, however few studies have been conducted on analytical modelling to characterise the crushing history of origami tubes under axial compression. Therefore, this work aims to build the analytical models of origami tubes under quasi-static compression and dynamic impact in the axial direction, based on the observation of deformation mechanisms. Miura pattern was employed to construct the origami tubes;single-layer and multi-layer models were considered. Analytical models were established with the assumption of rigid origami. Finite element (FE) simulations were carried out for validation and comparison. The crushing history of the multi-layer model was discussed. © 2024, The Authors. All rights reserved.

关键词： Energy absorption

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Effect of atomic structure on preferential oxidation of alloys:amorphous versus crystalline Cu-Zr

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Journal of Materials science & technology 2020年第5期40卷 128-134页

作者： Yifei Xu Lars P.H.Jeurgens Peter Schützendübe Shengli Zhu Yuan Huang Yongchang Liu Zumin Wang State Key Lab of Hydraulic Engineering Simulation and Safety School of Materials Science and EngineeringTianjin UniversityTianjin 300350China Swiss Federal Laboratories for Materials Science and Technology Laboratory for Joining Technologies and CorrosionUeberlandstrasse 1298600 DuebendorfSwitzerland Max Planck Institute for Intelligent Systems Heisenbergstrasse 3D-70569 StuttgartGermany

The effect of structural order in the parent alloy substrate on the oxidation kinetics and oxide phase evolution was investigated for the thermal oxidation of amorphous Cu33at.%Zr67at.%and crystalline CuZr2 alloys of identical compositions in the temperature range of 200–250?*** was found that,besides the strong preferential oxidation of Zr in both alloys,the lack of structural order in the amorphous Cu33at.%Zr67at.%alloy results in much slower oxidation kinetics,as well as in distinctly different microstructures of the oxide overgrowth and its Zr-depletion zone in the wake of the ZrO2 overlayer growth *** experimental findings can be rationalized on the basis of the strikingly different atomic mobilities of Cu,Zr and dissolved O in the amorphous and crystalline alloys,which also results in different nucleation barriers for crystalline oxide *** thus obtained knowledge on the underlying oxidation mechanisms provides new and profound insights into the surface engineering of metallic alloys.

关键词： Oxidation Atomic structure Amorphous alloys Cu-Zr HRTEM

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Structure-function based study on the logarithmic region in atmospheric surface layer with and without sand

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Physical Review Fluids 2022年第8期7卷 084609-084609页

作者： Fei-Chi Zhang Jin-Han Xie Xiaojing Zheng Department of Mechanics and Engineering Science at College of Engineering and State Key Laboratory for Turbulence and Complex Systems Peking University Beijing 100871 People's Republic of China Joint Laboratory of Marine Hydrodynamics and Ocean Engineering Pilot National Laboratory for Marine Science and Technology (Qingdao) Shandong 266237 People's Republic of China Center for Particle-Laden Turbulence Lanzhou University Lanzhou 730000 People's Republic of China

In the logarithmic layer of boundary-layer turbulence, velocity structure functions scale as power and logarithmic functions of displacement at small and large scales, respectively. The small-scale scaling can be explained as a near-isotropy behavior, while the mechanism behind the logarithmic behavior is debatable. By rescaling the horizontal displacement by the distance to the wall, using the attached eddy hypothesis to the Kármán-Howarth-Monin (KHM) equation results in the logarithmic behavior. Also, from the picture of energy cascade, i.e., introducing a characteristic scale uτ3/ε with uτ and ε the friction velocity and energy dissipation rate, respectively, the logarithmic profile of the third-order structure function can also be obtained. These two explanations suggest a dependence of the third-order structure function on the difference between local production and dissipation. By analyzing data measured from the Qingtu Lake Observation Array built on a dry flatbed of Qingtu Lake in Minqin (China) with Reτ=O(106), we provide evidence for the scaling behaviors and justify the underlying balances in the range with large displacements. And we study the robustness of the structure function theory using clear-air and sand-containing data: sands modify key statistical quantities of the boundary-layer turbulence, such as the height dependence of the Reynolds stress, but the behavior of the third-order structure function remains unchanged. Considering that the shear production captures the strength of anisotropic perturbation-mean interaction in the KHM equation, the ratio of production and dissipation controls the relative extensions of the power and logarithmic ranges, and a stronger production leads to a relatively wider logarithmic range, which is justified by measured data.

关键词： Atmospheric fluid dynamics Particle-laden flows Structure & turbulence of boundary layers

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Multiple stochastic resonances and inverse stochastic resonances in asymmetric bistable system under the ultra-high frequency excitation

arXiv

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arXiv 2024年

作者： Wang, Cong Wang, Zhongqiu Yang, Jianhua Sanjuán, Miguel A.F. Tao, Gong Shan, Zhen Shen, Mengen Jiangsu Key Laboratory of Mine Mechanical and Electrical Equipment School of Mechatronic Engineering China University of Mining and Technology Xuzhou221116 China School of Computer Science and Technology China University of Mining and Technology Xuzhou221116 China Nonlinear Dynamics Chaos and Complex Systems Group Departamento de Física Universidad Rey Juan Carlos Tulipán s/n Móstoles Madrid28933 Spain

Ultra-high frequency linear frequency modulation (UHF-LFM) signal, as a kind of typical non-stationary signal, has been widely used in microwave radar and other fields, with advantages such as long transmission distance, strong anti-interference ability, and wide bandwidth. Utilizing optimal dynamics response has unique advantages in weak feature identification under strong background noise. We propose a new stochastic resonance method in an asymmetric bistable system with the time-varying parameter to handle this special non-stationary signal. Interestingly, the nonlinear response exhibits multiple stochastic resonances (MSR) and inverse stochastic resonances (ISR) under UHF-LFM signal excitation, and some resonance regions may deviate or collapse due to the influence of system asymmetry. In addition, we analyze the responses of each resonance region and the mechanism and evolution law of each resonance region in detail. Finally, we significantly expand the resonance region within the parameter range by optimizing the time scale, which verifies the effectiveness of the proposed time-varying scale method. The mechanism and evolution law of MSR and ISR will provide references for researchers in related fields. © 2024, CC BY.

关键词： Stochastic systems

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BrainWave: A Brain Signal Foundation Model for Clinical Applications

arXiv

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arXiv 2024年

作者： Yuan, Zhizhang Shen, Fanqi Li, Meng Yu, Yuguo Gu, Gefei Wu, Fei Tan, Chenhao Yang, Yang Zhejiang University Zhejiang Hangzhou China Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai China INSIDE Institute for Biological and Artificial Intelligence Shanghai China Research Institute of Intelligent and Complex Systems State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science Institute of Science and Technology for Brain-Inspired Intelligence Fudan University Shanghai China Shanghai Artificial Intelligence Laboratory Fudan University Shanghai China University of Chicago ChicagoIL United States

Neural electrical activity is fundamental to brain function, underlying a range of cognitive and behavioral processes, including movement, perception, decision-making, and consciousness. Abnormal patterns of neural signaling often indicate the presence of underlying brain diseases. The variability among individuals, the diverse array of clinical symptoms from various brain disorders, and the limited availability of diagnostic classifications, have posed significant barriers to formulating reliable model of neural signals for diverse application contexts. Here, we present BrainWave, the first foundation model for both invasive and noninvasive neural recordings, pretrained on more than 40,000 hours of electrical brain recordings (13.79 TB of data) from approximately 16,000 individuals. Our analysis show that BrainWave outperforms all other competing models and consistently achieves state-of-the-art performance in the diagnosis and identification of neurological disorders. We also demonstrate robust capabilities of BrainWave in enabling zero-shot transfer learning across varying recording conditions and brain diseases, as well as few-shot classification without fine-tuning, suggesting that BrainWave learns highly generalizable representations of neural signals. We hence believe that open-sourcing BrainWave will facilitate a wide range of clinical applications in medicine, paving the way for AI-driven approaches to investigate brain disorders and advance neuroscience research. Copyright © 2024, The Authors. All rights reserved.

关键词： Zero-shot learning

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In-Situ Study of the Heating Rate Effects on Covalent Bonds Conversion and Pores/Carbon Microcrystals Evolution of Coal Molecules During Coking

SSRN

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SSRN 2023年

作者： Cui, Beibei Wang, Meijun Zheng, Mo Li, Zhihong Jin, Xin Shen, Yanfeng Chang, Liping State Key Laboratory of Clean and Efficient Coal Utilization Taiyuan University of Technology Taiyuan030024 China Key Laboratory of Coal Science and Technology Ministry of Education Taiyuan University of Technology Taiyuan030024 China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China Beijing Synchrotron Radiation Facility Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China

The impact of pyrolysis reaction environment on coal coking behavior contributes to comprehensive understanding of coking mechanism and oriented regulation on coke-making process. The decomposition of coal molecules and the thermal cleavage of covalent bonds under various heating rates were analyzed using the TGA technique combined with the ReaxFF MD method. The heating rate effects on micro-level structural evolution of coal macromolecules was revealed based on the abundance evolution of covalent bonds. Particularly, the evolutions of pore and carbon structures of coal particles during coking were in-situ investigated using the synchrotron radiation small angle X-ray scattering (SAXS) in conjunction with wide angle X-ray scattering (WAXS) techniques. The analyses reveal that rapid heating facilitates hydrogen bonds disruption and reduces the van der Waals interaction among coal macromolecules, leading to the relaxation of cohesive structure and the presence of mobile hydrogen residue in coal before 400 oC. In addition, the high heating rate promotes the breakage of Cal-Cal/H and Car-Cal bonds while impends rupture of Cal-O, Car-O and Car-Car bonds, which contributes to the stabilization of radicals and enhances the formation of plastic mass. The rapid pyrolysis affects the delicate equilibrium between disturbance of volatiles escape and orientation of plastic mass fluidity, thereby determining the development of mesoscopic structures of semi-cokes. This work is expected to demonstrate the rationality of "Structure Derivation Coking Mechanism" and offer scientific foundation for regulating the coking behavior in various coke ovens. © 2023, The Authors. All rights reserved.

关键词： Synchrotron radiation

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A Reinforcement Learning Based Dynamic Multi-Objective Constrained Evolutionary Algorithm for Open-Pit Mine Truck Scheduling

A Reinforcement Learning Based Dynamic Multi-Objective Const...

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Chinese Automation Congress (CAC)

作者： Junxiang Qiu Changhe Li Shengxiang Yang Engineering Research Center of Intelligent Technology for Geo- Exploration Ministry of Education School of Automation China University of Geosciences Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems Wuhan China School of Computer Science and Informatics De Montfort University Leicester UK

Aiming at the truck scheduling problem in the open-pit mine scenario, a truck scheduling model based on real-time ore blending is established, and an adaptive evolution algorithm for truck scheduling based on DCNSGA-III is proposed. In the established scheduling model, the real-time grade variance of the crushing plant is minimized as one of the optimization objectives, and the Q-learning algorithm is introduced to adaptively select one of the most effective operators during the search process. Experiments show that the proposed method can effectively control the grade fluctuation of the ore flow and better scheduling schemes are obtained in comparison with algorithms equipped with the traditional search operator selection methods.

关键词：

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长江流域城市水污染治理成效的系统评估与解析

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Engineering 2023年第2期21卷 135-142,M0006页

作者：齐维晓王旭康瑾柏耀辉边睿薛弘涛陈莉关傲梅潘艺蓉刘会娟曲久辉 Center for Water and Ecology State Key Joint Laboratory of Environment Simulation and Pollution ControlSchool of EnvironmentTsinghua UniversityBeijing 100084China State Key Laboratory of Urban Water Resource and Environment School of Civil and Environmental EngineeringHarbin Institute of TechnologyShenzhenShenzhen 518055China Centre for Water Systems College of EngineeringMathematics and Physical SciencesUniversity of ExeterExeter EX44QFUK Hubei Provincial Research Institute of Environmental Science Wuhan 430072China Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China

如何实现人类社会经济的可持续发展是本世纪的重大挑战之一。近几十年来,中国经济实力大幅提升,国际影响力显著增强。然而,经济社会高速发展可能会给生态环境造成诸多不利影响,其中之一就是人类活动污水排放总量的快速增长。长江经济带... 详细信息

如何实现人类社会经济的可持续发展是本世纪的重大挑战之一。近几十年来,中国经济实力大幅提升,国际影响力显著增强。然而,经济社会高速发展可能会给生态环境造成诸多不利影响,其中之一就是人类活动污水排放总量的快速增长。长江经济带作为中国高质量发展的重点区域,科学评估和揭示沿江城市群污水治理成效及影响因素至关重要。本研究核算了2007-2017年间长江流域主要污染物的浓度变化趋势,利用数据驱动型技术对影响污染物通量变化的关键因子及其贡献开展了系统解耦和量化分析,揭示了污染物排放强度的时空异质性,解析了沿江城镇污水系统发展对污染物通量削减的作用效果。研究发现,长江流域水污染治理成效总体向好,长江经济带国内生产总值和沿江人类活动污水排放强度之间的强耦合在2013年之后呈现脱钩趋势,这主要得益于城镇排水和污水厂基础设施建设的快速发展。研究提出,长江流域城镇污水治理如何实现以水载资源再生利用为导引的“绿色零碳模式”转变,对于全面改善长江流域的水环境质量具有关键作用,同时也能为区域生态环境保护与经济高质量发展提供有益启示和借鉴。

关键词：国内生产总值长江经济带资源再生利用系统评估治理成效时空异质性中国经济实力城镇排水

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Remote Operation with Haptic Force and Virtual Proxy for an Underwater Vehicle-Manipulator System 10

Remote Operation with Haptic Force and Virtual Proxy for an ...

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10th IEEE Data Driven Control and Learning systems Conference, DDCLS 2021

作者： Ma, Jin Wang, Yu Wang, Rui Wang, Shuo University of Chinese Academy of Sciences Beijing100049 China State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences Beijing100190 China Cas Center for Excellence in Brain Science and Intelligence Technology Shanghai200031 China

ISBN: (纸本)9781665424233

This paper aims to investigate a smooth teleoperation method for the underwater vehicle-manipulator system. First, a coordinated mapping control method for the vehicle is presented. The haptic force is considered to help assist the operation. Then, two mapping modes are used to teleoperate the manipulator: when the end-effector needs to move in a large area, two virtual points and a spring-damping system are implemented to filter the operator's hand jitter and limit the manipulator's speed;when the end-effector needs to move in a small area, a position increment control method with a small proportional coefficient is used to improve the precision. Finally, the simulation demonstrates the effectiveness of the proposed teleoperation method. © 2021 IEEE.

关键词： Manipulators

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Particle-Scale Modelling of Injected Hydrogen and Coke Co-Combustion in the Raceway of an Ironmaking Blast Furnace

SSRN

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SSRN 2022年

作者： Dianyu, E. Zhou, Peng Ji, Langyong Cui, Jiaxin Xu, Qiang Guo, Liejin Yu, Aibing International Institute for Innovation Jiangxi University of Science and Technology Ganzhou341000 China Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Jiangxi University of Science and Technology Ganzhou341000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China ARC Research Hub for Computational Particle Technology Department of Chemical Engineering Monash University VIC3800 Australia Centre for Simulation and Modelling of Particulate Systems Southeast University Monash University Joint Research Institute Suzhou215123 China

Hydrogen is an environmentally friendly fuel that does not produce greenhouse gas (GHG) emissions. Its applications have attracted significant attention from many industries, especially the ironmaking industry, which consumes massive amounts of fossil energy. The injection of hydrogen into a blast furnace (BF) is one of the most promising low-carbon ironmaking routines. In this study, an experimentally validated CFD-DEM model is adopted to investigate the dynamics, microstructure and thermochemical behaviours in the raceway of a BF with hydrogen injection operations (HIOs), which include raceway evolution, force distribution and the co-combustion characteristics of hydrogen and coke. Some significant features are obtained through comparison analyses between HIOs and air injection operations (AIOs). In particular, the effects of the hydrogen injection concentration on the raceway size, gas temperature and components are studied. The simulation results show that a smaller raceway is formed under HIOs in comparison with that of AIOs. In addition, the gas temperature is higher near the tuyere but lower along the tuyere axis, and the oxygen consumption is larger and produces more CO. As the hydrogen injection concentration increases: (i) the raceway size and gas temperature decrease;(ii) the CO is generated at the early stage and the maximum CO2 concentration moves to inlet direction along the tuyere axis. The results provide insights on the fundamental understanding of low-carbon ironmaking BF technology. © 2022, The Authors. All rights reserved.

关键词： Blast furnaces

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