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Interface failure of segmental tunnel lining strengthened with steel plates based on fracture mechanics

Frontiers of Structural and Civil Engineering 2024年第1期18卷 137-149页

作者： Yazhen sun Yang YU Jinchang WANG Longyan WANG School of Transportation and Geomatics Engineering Shenyang Jianzhu UniversityShenyang 110168China School of Civil Engineering Shenyang Jianzhu UniversityShenyang 110168China Institute of Transportation Engineering Zhejiang UniversityHangzhou 310058China Center for Balance Architecture Zhejiang UniversityHangzhou310058China

Segmental tunnel lining strengthened with steel plates is widely used worldwide to provide a permanent strengthening *** existing studies assume an ideal steel-concrete interface,ignoring discontinuous deformation characteristics,making it difficult to accurately analyze the strengthened structure’s failure *** this study,interfacial fracture mechanics of composite material was applied to the segmental tunnel lining strengthened with steel plates,and a numerical three-dimensional solid nonlinear model of the lining structure was established,combining the extended finite element method with a cohesive-zone model to account for the discontinuous deformation characteristics of the *** results accurately describe the crack propagation process,and are verified by full-scale ***,dynamic simulations based on the calibrated model were conducted to analyze the sliding failure and cracking of the steel-concrete ***,detailed location of the interface bonding failure are further verified by model *** results show that,the cracking failure and bond failure of the interface are the decisive factors determining the instability and failure of the strengthened *** proposed numerical analysis is a major step forward in revealing the interface failure mechanism of strengthened composite material structures.

关键词： segmental tunnel lining steel plate strengthening connecting interface cohesive-zone model extended finite element method

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Numerical study on the cavity dynamics for vertical water entries of twin spheres

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Defence Technology（防务技术） 2024年第2期32卷 459-472页

作者： Xu Wang Xujian Lyu Ruisheng sun Dongdong Tang School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjing210094China Shanghai Institute of Spacecraft Equipment Shanghai200240China

In this study, a three dimensional(3D) numerical model of six-degrees-of-freedom(6DOF) is applied to simulate the water entries of twin spheres side-by-side at different lateral distances and time *** turbulence structure is described using the shear-stress transport k-ω(SST k-ω) model, and the volume of fluid(VOF) method is used to track the complex air-liquid interface. The motion of spheres during water entry is simulated using an independent overset grid. The numerical model is verified by comparing the cavity evolution results from simulations and experiments. Numerical results reveal that the time interval between the twin water entries evidently affects cavity expansion and contraction behaviors in the radial direction. However, this influence is significantly weakened by increasing the lateral distance between the two spheres. In synchronous water entries, pressure is reduced on the midline of two cavities during surface closure, which is directly related to the cavity volume. The evolution of vortexes inside the two cavities is analyzed using a velocity vector field, which is affected by the lateral distance and time interval of water entries.

关键词： Twin water entries Side-by-side Cavity Numerical simulation

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Refinement modeling and verification of secure operating systems for communication in digital twins

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Digital Communications and Networks 2024年第2期10卷 304-314页

作者： Zhenjiang Qian Gaofei sun Xiaoshuang Xing Gaurav Dhiman School of Computer Science and Engineering Changshu Institute of TechnologySuzhou215500China University Centre for Research and Development Department of Computer Science and EngineeringChandigarh UniversityMohali140413India Department of Computer Science and Engineering Graphic Era Deemed to be UniversityDehradun248002India

In traditional digital twin communication system testing,we can apply test cases as completely as possible in order to ensure the correctness of the system implementation,and even then,there is no guarantee that the digital twin communication system implementation is completely *** verification is currently recognized as a method to ensure the correctness of software system for communication in digital twins because it uses rigorous mathematical methods to verify the correctness of systems for communication in digital twins and can effectively help system designers determine whether the system is designed and implemented *** this paper,we use the interactive theorem proving tool Isabelle/HOL to construct the formal model of the X86 architecture,and to model the related assembly *** verification result shows that the system states obtained after the operations of relevant assembly instructions is consistent with the expected states,indicating that the system meets the design expectations.

关键词： Theorem proving Isabelle/HOL Formal verification System modeling Correctness verification

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Non-Convex Optimization of Resource Allocation in Fog Computing Using Successive Approximation

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Journal of Systems Science & Complexity 2024年第2期37卷 805-840页

作者： LI Shiyong LIU Huan LI Wenzhe sun Wei School of Economics and Management Yanshan UniversityQinhuangdao 066000China

Fog computing can deliver low delay and advanced IT services to end users with substantially reduced energy ***,with soaring demands for resource service and the limited capability of fog nodes,how to allocate and manage fog computing resources properly and stably has become the ***,the paper investigates the utility optimization-based resource allocation problem between fog nodes and end users in fog *** authors first introduce four types of utility functions due to the diverse tasks executed by end users and build the resource allocation model aiming at utility ***,for only the elastic tasks,the convex optimization method is applied to obtain the optimal results;for the elastic and inelastic tasks,with the assistance of Jensen’s inequality,the primal non-convex model is approximated to a sequence of equivalent convex optimization problems using successive approximation ***,a two-layer algorithm is proposed that globally converges to an optimal solution of the original ***,numerical simulation results demonstrate its superior performance and *** with other works,the authors emphasize the analysis for non-convex optimization problems and the diversity of tasks in fog computing resource allocation.

关键词： Fog computing non-convex optimization optimal resource allocation successive approximation method utility function

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Effect of structural characteristics on the transport characteristics of solid particles in the thermal storage and release system of circulating fluidized bed

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Particuology 2024年第6期89卷 22-31页

作者： Zengcai Ji Guoliang Song Zihua Tang Liwei sun Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China Dalian National Laboratory for Clean Energy Dalian116023China

Coal-fired power generation stands as the most economically viable modulating power source in present-day *** holds the potential to offer prospective solutions to the challenges posed by the rapid expansion of intermittent,unpredictable,and unstable renewable energy *** particle thermal storage technology emerges as an effective means to enhance the flexibility of coal-fired circulating fluidized bed power *** attain an optimized structure for the solid particle thermal storage and release system in circulating fluidized bed units,experimental research was conducted on a 0.1 MWth circulating fluidized bed test *** study delved into the impact of ash storage bin geometries and the shapes of their feed-discharge valves on the control properties of solid particle *** experimental outcomes reveal that employing inverted m-shaped valve and dual U-shaped valves for feed control,alongside U-shaped valves and N-shaped valves for discharge control,both enable efficient and rapid storage and release of solid particles within the circulating fluidized *** similar air distribution conditions,the inverted m-shaped valve exhibits lower conveying energy consumption than the dual U-shaped valves,while the N-shaped valve excels in control characteristics over the U-shaped ***,the inverted m-shaped valve and the N-shaped valve demonstrate optimal overflow port heights,and the ash storage bin exhibits an optimum height-to-diameter ratio.

关键词： Solid particle Thermal storage System structure Transport regulation

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Passivity-Based Stabilization for Switched Stochastic Nonlinear Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1307-1309页

作者： Yaowei sun Jun Zhao School of Automation Zhengzhou University of AeronauticsZhengzhou 450046 Henan Key Laboratory of General Aviation Technology Zhengzhou University of AeronauticsZhengzhou 450046China College of Information Science and Engineering Northeastern UniversityShenyang 110819China

Dear Editor,This letter addresses the passivity-based mean square exponential stabilization problem for switched stochastic nonlinear systems.A concept of generalized small-time norm-observability is presented and an appropriate test condition is also *** pre-given passivity rate and average dwell time,a set of feedback controllers is designed by use of the passivity property.

关键词： property letter stabilization

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两类El Niňo事件盛期南大洋海冰异常的对比分析

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气候与环境研究 2022年第3期27卷 436-446页

作者：王卓凡韩哲李双林李国平孙雪倩成都信息工程大学大气科学学院成都610225 中国科学院大气物理研究所北京100029

基于1979~2017年数据,利用回归方法和线性模式试验,分析了两类El Niño事件(东部型EP和中部型CP)盛期(12月至2月)南大洋海冰异常的差异及其可能机制。结果表明,两类事件期间尽管海冰异常定性上类似,但强度和位置存在明显差异:在罗斯海和... 详细信息

基于1979~2017年数据,利用回归方法和线性模式试验,分析了两类El Niño事件(东部型EP和中部型CP)盛期(12月至2月)南大洋海冰异常的差异及其可能机制。结果表明,两类事件期间尽管海冰异常定性上类似,但强度和位置存在明显差异:在罗斯海和阿蒙森海,两类事件期间海冰均偏少,但EP期间海冰减少范围更大,振幅更强;在威德尔海,两类事件期间海冰均偏多,但EP期间增多更明显,而且位置相对CP期间偏西偏北。造成这种差异的主要因素是两类事件期间海温异常强度的不同:EP期间对应的海温偏东偏强,其激发的类太平洋—南美型(PSA)模态在南极边缘海的异常高压中心强度更大、范围更广,使得罗斯海区域为东北风异常控制,有利海冰向高纬输送,海冰范围进而减少;而威德尔海区域则是异常偏南风控制,使得海冰向北输送,有利于威德尔海南部海冰范围减少,北部海冰范围增大。相比之下,CP事件期间,赤道中东太平洋的暖海温异常偏于中太平洋且强度弱,其激发的类PSA在南极边缘的异常高压偏弱,使得动力作用引起阿蒙森海的海冰减少和威德尔海海冰增加偏弱。进一步的分析表明,CP事件期间威德尔海海冰增多还与该区域更早时间(11月份)的海冰增多,及随后海冰—太阳反照率的正反馈效应有关。本研究结果显示两类事件期间海冰异常的强度和位置的差异,与两类事件期间赤道中东太平洋SSTA强度和位置的差异,二者有很好的对应关系,相比前人的合成分析结果(CP期间海冰异常强于EP期间),物理上更为合理。

关键词：东部型厄尔尼诺中部型厄尔尼诺南极海冰遥相关太平洋—南美型(PSA)

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Design and Control of an Autonomous Bat-like Perching UAV

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Journal of Bionic Engineering 2024年第3期21卷 1253-1264页

作者： Long Bai Wei Wang Xiaohong Chen Yuanxi sun State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing400044China

Perching allows small Unmanned Aerial Vehicles(UAVs)to maintain their altitude while significantly extending their flight duration and reducing ***,current research on flying habitats is poorly adapted to unstructured environments,and lacks autonomous capabilities,requiring ideal experimental environments and remote control by *** solve these problems,in this paper,we propose a bat-like UAV perching mechanism by investigating the bat upside-down perching method,which realizes double self-locking in the perching state using the ratchet and four-link dead point *** on this perching mechanism,this study proposes a control strategy for UAVs to track targets and accomplish flight perching autonomously by combining a binocular camera,single-point LiDAR,and pressure *** perching experiments were conducted for crossbar-type objects *** experimental results show that a multirotor UAV equipped with the perching mechanism and sensors can reliably achieve autonomous flight perching and re-flying off the target *** power consumption is reduced to 2.9%of the hovering state when perched on the target object.

关键词： Bio-inspired design Perching mechanism UAV Autonomous flight

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Influence of calendering process on the structural mechanics and heat transfer characteristics of lithium-ion battery electrodes via DEM simulations

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Particuology 2024年第2期85卷 252-267页

作者： Junpeng Zhang Jingna sun Huagui Huang Zhenge Yuan National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao066004China Xingtai Naknor Technology Co. LtdXingtai054000China

Elucidating the intricate correlation between calendering,structure,and performance is crucial to comprehending the relationship between performance parameters and process steps of lithium-ion batteries(LIBs).Discrete element method(DEM)simulations were adopted in this work to calculate the interparticle force and stress tensor under incremental calendering process conditions,which revealed the effect of the anisotropy of complex contact force network on the anisotropy of heat transfer within porous *** thermal conductivity of electrode was predicted using porosity to characterize the process-structure-performance *** comprehensive influence of contact number and con-tact area between particles and current collector determines the magnitude of interfacial thermal resistance and interfacial heat transfer *** the first time,this work quantitatively analyzed the structural mechanics and heat transfer mechanism during calendering process of porous electrodes,and the results indicate a promising way to optimize and design battery electrode structures.

关键词： Li-ion battery electrode Structural mechanicsAnisotropy Thermal conductivity Discrete element method

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Achieving Negatively Charged Pt Single Atoms on Amorphous Ni(OH)_(2)Nanosheets with Promoted Hydrogen Absorption in Hydrogen Evolution

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Nano-Micro Letters 2024年第10期16卷 213-224页

作者： Yue Liu Gui Liu Xiangyu Chen Chuang Xue Mingke sun Yifei Liu Jianxin Kang Xiujuan sun Lin Guo School of Chemistry Beijing Advanced Innovation Center for Biomedical EngineeringKey Laboratory of Bio-inspired Smart Interfacial Science and TechnologyBeihang UniversityBeijing 100191People's Republic of China School of Chemistry Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of EducationXiangtan UniversityXiangtan 411105HunanPeople'Republic of China

Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and ***,most of the reported SA catalysts are fixed through the strong bonding between the dispersed single metallic atoms with nonmetallic atoms of the substrates,which greatly limits the controllable regulation of electrocatalytic activity of SA *** this work,Pt-Ni bonded Pt SA catalyst with adjustable electronic states was successfully constructed through a controllable electrochemical reduction on the coordination unsaturated amorphous Ni(OH)_(2)nanosheet *** on the X-ray absorption fine structure analysis and first-principles calculations,Pt SA was bonded with Ni sites of amorphous Ni(OH)_(2),rather than conventional O sites,resulting in negatively charged Pt^(δ-).In situ Raman spectroscopy revealed that the changed configuration and electronic states greatly enhanced absorbability for activated hydrogen atoms,which were the essential intermediate for alkaline hydrogen evolution *** hydrogen spillover process was revealed from amorphous Ni(OH)_(2)that effectively cleave the H-O-H bond of H_(2)O and produce H atom to the Pt SA sites,leading to a low overpotential of 48 mV in alkaline electrolyte at-1000 mA cm^(-2)mg^(-1)_(Pt),evidently better than commercial Pt/C *** work provided new strategy for the control-lable modulation of the local structure of SA catalysts and the systematic regulation of the electronic states.

关键词： Hydrogen evolution reaction Amorphous Pt single atoms Hydrogen spillover

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