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Cyclic shear behavior of en-echelon joints under constant normal stiffness conditions

Journal of Rock Mechanics and geotechnical {1. 2024年第9期16卷 3419-3436页

作者： Bin Wang Yujing Jiang Qiangyong Zhang Hongbin Chen Richeng Liu Yuanchao Zhang Graduate School of engineering Nagasaki UniversityNagasaki852-8521Japan Research Center of geotechnical and Structural {1. Shandong UniversityJi’nan250061China State Key Laboratory for Geomechanics and Deep Underground engineering China University of Mining and TechnologyXuzhou221116China College of Civil engineering Fuzhou UniversityFuzhou350108China

To reveal the mechanism of shear failure of en-echelon joints under cyclic loading,such as during earthquakes,we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness(CNS)*** analyzed the evolution of shear stress,normal stress,stress path,dilatancy characteristics,and friction coefficient and revealed the failure mechanisms of en-echelon joints at different *** results show that the cyclic shear behavior of the en-echelon joints is closely related to the joint angle,with the shear strength at a positive angle exceeding that at a negative angle during shear *** the number of cycles increases,the shear strength decreases rapidly,and the difference between the varying angles gradually *** occurs in the early shear cycles(1.and 2),while contraction is the main feature in later cycles(31.).The friction coefficient decreases with the number of cycles and exhibits a more significant sensitivity to joint angles than shear *** joint angle determines the asperities on the rupture surfaces and the block size,and thus determines the subsequent shear failure mode(block crushing and asperity degradation).At positive angles,block size is more greater and asperities on the rupture surface are smaller than at nonpositive ***,the cyclic shear behavior is controlled by block crushing at positive angles and asperity degradation at negative angles.

关键词： En-echelon joint Cyclic shear tests Shear stress Normal displacement Constant normal stiffness(CNS)

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Thermo-hydro-poro-mechanical responses of a reservoir-induced landslide tracked by high-resolution fiber optic sensing nerves

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Journal of Rock Mechanics and geotechnical {1. 2024年第3期16卷 1018-1032页

作者： Xiao Ye Hong-Hu Zhu Gang Cheng Hua-Fu Pei Bin Shi Luca Schenato Alessandro Pasuto School of Earth Sciences and engineering Nanjing UniversityNanjing210023China School of Computer Science North China Institute of Science and Technology(National Safety Training Center of Coal Mines)Beijing101601China State Key Lab of Coastal and Offshore engineering Department of Geotechnical EngineeringDalian University of TechnologyDalian116024China National Research Council-Research Institute for Geo-Hydrological Protection(CNR-IRPI) Padova35127Italy department of Information {1. University of PadovaPadova35131Italy

Thermo-poro-mechanical responses along sliding zone/surface have been extensively ***,it has not been recognized that the potential contribution of other crucial engineering geological interfaces beyond the slip surface to progressive ***,we aim to investigate the subsurface multiphysics of reservoir landslides under two extreme hydrologic conditions(*** and dry),particularly within sliding *** on ultra-weak fiber Bragg grating(UWFBG)technology,we employ specialpurpose fiber optic sensing cables that can be implanted into boreholes as“nerves of the Earth”to collect data on soil temperature,water content,pore water pressure,and *** Xinpu landslide in the middle reach of the Three Gorges Reservoir Area in China was selected as a case study to establish a paradigm for in situ thermo-hydro-poro-mechanical *** UWFBG-based sensing cables were vertically buried in a 31.m-deep borehole at the foot of the landslide,with a resolution of 1.m except for the pressure *** reported field measurements covering the period 2021.and 2022 and produced the spatiotemporal profiles throughout the *** show that wet years are more likely to motivate landslide motions than dry *** annual thermally active layer of the landslide has a critical depth of roughly 9 m and might move downward in warmer *** dynamic groundwater table is located at depths of 9e1. m,where the peaked strain undergoes a periodical response of leap and withdrawal to annual hydrometeorological *** interface behaviors may support the interpretation of the contribution of reservoir regulation to slope stability,allowing us to correlate them to local damage events and potential global *** paper also offers a natural framework for interpreting thermo-hydro-poro-mechanical signatures from creeping reservoir bank slopes,which may form the basis for a landslide monitoring and early warning system.

关键词： Reservoir landslide Thermo-hydro-poro-mechanical response Ultra-weak fiber bragg grating(UWFBG) subsurface evolution engineering geological interface geotechnical monitoring

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Development of a Three-Dimensional Multiscale Octree SBFEM for Viscoelastic Problems of Heterogeneous Materials

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Computer Modeling in engineering & Sciences 2024年第8期140卷 1831-1861页

作者： Xu Xu Xiaoteng Wang Haitian Yang Zhenjun Yang Yiqian He State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDepartment of Engineering MechanicsDalian University of TechnologyDalian116024China Hubei Key Laboratory of geotechnical and Structural Safety School of Civil EngineeringWuhan UniversityWuhan430072China Mechanik–Materialtheorie Ruhr-Universität BochumBochum44801Germany

The multiscale method provides an effective approach for the numerical analysis of heterogeneous viscoelastic materials by reducing the degree of freedoms(DOFs).A basic framework of the Multiscale Scaled Boundary Finite Element Method(MsSBFEM)was presented in our previous works,but those works only addressed two-dimensional *** order to solve more realistic problems,a three-dimensional MsSBFEM is further developed in this *** the proposed method,the octree SBFEM is used to deal with the three-dimensional calculation for numerical base functions to bridge small and large scales,the three-dimensional image-based analysis can be conveniently conducted in small-scale and coarse nodes can be flexibly adjusted to improve the computational ***,the Temporally Piecewise Adaptive Algorithm(TPAA)is used to maintain the computational accuracy of multiscale analysis by adaptive calculation in time *** results of numerical examples show that the proposed method can significantly reduce the DOFs for three-dimensional viscoelastic analysis with good *** instance,the DOFs can be reduced by 9021.times compared with Direct Numerical Simulation(DNS)with an average error of 1.87%in the third example,and it is very effective in dealing with three-dimensional complex microstructures directly based on images without any geometric modelling process.

关键词： Three-dimensionalmultiscale viscoelastic analysis numerical base functions octree SBFEM image-based analysis temporally piecewise adaptive algorithm

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Formation adaptation in obstacle-cluttered environments via MPC-based trajectory planning

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Science China(Information Sciences) 2024年第7期67卷 321-323页

作者： Yuda CHEN Zhongkui LI department of Mechanics and {1. Science College of Engineering Peking University

Formation is a typical collective behavior in multiagent systems utilized in areas such as inspection, surveillance, and transportation. Commonly-used approaches to achieve formation include virtual structure [1., con...

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An Experimental Study on Response and Control of a Flapping-Wing Aerial Robot Under Wind Gusts

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Journal of Bionic engineering 2024年第1期21卷 209-223页

作者： Kazuki Shimura Hikaru Aono Chang-kwon Kang Graduate School of Science and Technology Shinshu University3-15-1 TokidaUedaNagano 3868567Japan department of Mechanical {1. and Robotics 3-15-1 TokidaUedaNagano 3868567Japan department of Mechanical and Aerospace {1. University of Alabama in HuntsvilleTechnology Hall N266HuntsvilleAL35899USA

Bioinspired flapping-wing micro-air-vehicles(FWMAVs)have the potential to be useful aerial tools for gathering information in various *** recent advancements in manufacturing technologies and better understanding of aerodynamic mechanisms behind of the flapping flight,outdoor flights have become a ***,to fully realize the potential of FWMAVs,further improvements are necessary,particularly in terms of stability and robustness under gusty *** this study,the response and control of a tailless two-winged FWMAV under the wind gusts are *** experiments are conducted with a one-degree-of-freedom gimbal to focus on effects of wind gusts on the rotational motion of the ***-derivative and sliding-mode controls are adopted for the attitude *** present that the body angles changed in time and reached approximately 50°at the maximum due to the wing *** sliding-mode controller can more effectively control the rotational angle in the presence of disturbances and both the wing speed and changes in wind speed have an impact on the effectiveness of attitude *** results contribute to the development of of tailless two-winged,single-motor driven FWMAVs in terms of the design of attitude controller and testing apparatus.

关键词： Flapping-wing micro-air vehicles Sliding-mode control Pitch and roll angle-Wind gus

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Confluence of ZnO and PTFE Binder for Enhancing Performance of Thin-Film Lithium-Ion Batteries

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Energy & Environmental Materials 2024年第5期7卷 52-60页

作者： Subhashree Behera Swathi Ippili Venkatraju Jella Na-Yeong Kim Seong Cheol Jang Ji-Won Jung Soon-Gil Yoon Hyun-Suk Kim department of Materials Science and {1. Chungnam National University School of Materials Science and engineering University of Ulsan department of Energy and Materials {1. Dongguk University

Developing anode materials with high specific capacity and cycling stability is vital for improving thin-film lithium-ion batteries. Thin-film zinc oxide （ZnO）holds promise due to its high specific capacity, but it suffers from volume changes and structural stress during cycling, leading to poor battery performance. In this research, we ingeniously combined polytetrafluoroethylene （PTFE） with ZnO using a radio frequency （RF）magnetron co-sputtering method, ensuring a strong bond in the thin-film composite electrode. PTFE effectively reduced stress on the active material and mitigated volume change effects during Li+ion intercalation and deintercalation. The composite thin films are thoroughly characterized using advanced techniques such as X-ray diffraction, scanning electron microscopy,and X-ray photoelectron spectroscopy for investigating correlations between material properties and electrochemical behaviors. Notably, the ZnO/PTFE thin-film electrode demonstrated an impressive specific capacity of1.05 mAh g-1.=71.6 mAh cm-3) at a 0.5C rate and a remarkable capacity retention of 82%from the 1.t to the 1.0th cycle, surpassing the bare ZnO thin film （50%）. This study provides valuable insights into using binders to stabilize active materials in thin-film batteries, enhancing battery performance.

关键词： li-ion batteries metal oxides anodes polytetrafluoroethylene (PTFE) thin films

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Cybersecurity Landscape on Remote State Estimation:A Comprehensive Review

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IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 851-865页

作者： Jing Zhou Jun Shang Tongwen Chen the department of Electrical and Computer {1. University of AlbertaEdmonton AB T6G 1H9Canada the department of Control Science and {1. and Shanghai Research Institute for Intelligent Autonomous Systems Tongji UniversityShanghai 200092China

Cyber-physical systems(CPSs)have emerged as an essential area of research in the last decade,providing a new paradigm for the integration of computational and physical units in modern control *** state estimation(RSE)is an indispensable functional module of ***,it has been demonstrated that malicious agents can manipulate data packets transmitted through unreliable channels of RSE,leading to severe estimation performance *** paper aims to present an overview of recent advances in cyber-attacks and defensive countermeasures,with a specific focus on integrity attacks against ***,two representative frameworks for the synthesis of optimal deception attacks with various performance metrics and stealthiness constraints are discussed,which provide a deeper insight into the vulnerabilities of ***,a detailed review of typical attack detection and resilient estimation algorithms is included,illustrating the latest defensive measures safeguarding RSE from ***,some prevalent attacks impairing the confidentiality and data availability of RSE are examined from both attackers'and defenders'***,several challenges and open problems are presented to inspire further exploration and future research in this field.

关键词： Cyber-attacks Kalman filtering remote state estimation unreliable transmission channels

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From seawater to hydrogen via direct photocatalytic vapor splitting: A review on device design and system integration

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Frontiers in Energy 2024年第3期18卷 291-307页

作者： Hongxia LI Khaja WAHAB AHMED Mohamed A.ABDELSALAM Michael FOWLER Xiao-Yu WU Technology Innovation Institute Masdar CityAbu Dhabi 9639United Arab Emirates department of Chemical {1. University of WaterlooWaterlooON N2L 3G1Canada department of Mechanical and Nuclear {1. Khalifa University of Science and TechnologyAbu Dhabi 127788United Arab Emirates department of Mechanical and Mechatronics {1. University of WaterlooWaterlooON N2L 3G1Canada

Solar-driven hydrogen production from seawater attracts great interest for its emerging role in decarbonizing global energy consumption. Given the complexity of natural seawater content, photocatalytic vapor splitting offers a low-cost and safe solution, but with a very low solar-to-hydrogen conversion efficiency. With a focus on cutting-edge photothermal–photocatalytic device design and system integration, the recent research advances on vapor splitting from seawater, as well as industrial implementations in the past decades were reviewed. In addition, the design strategies of the key processes were reviewed, including vapor temperature and pressure control during solar thermal vapor generation from seawater, capillary-fed vaporization with salt repellent, and direct photocatalytic vapor splitting for hydrogen production. Moreover, the existing laboratory-scale and industrial-scale systems, and the integration principles and remaining challenges in the future seawater-to-hydrogen technology were discussed.

关键词： seawater hydrogen photocatalytic vapor splitting solar-driven

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Oblique impact breakage unification of nonspherical particles using discrete element method

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Particuology 2024年第7期90卷 61-71页

作者： Di Peng LiGe Wang Yuquan Lin Chongqiang Zhu Xizhong Chen Zhihui Liu Ruihuan Ge Shenzhen Research Institute of Shandong University Shenzhen 518057China Institute of Foundation engineering China Academy of Building ResearchBeijing 100013China Ubiquitous Particle Ltd. TwickenhamLondon TW27AUUK department of Smart Manufacturing and {1. Software School of Qilu TransportationShandong UniversityJinan 250061China department of {1. engineering Tongji UniversityShanghai 200092China School of Transportation and Civil engineering Shandong Jiaotong UniversityJinan 250357China School of Science and engineering University of DundeeDundee DD14HNUK department of Chemical {1. School of Chemistry and Chemical EngineeringShanghai Jiao Tong UniversityShanghai 200240China department of Chemical and Biological {1. University of SheffieldSheffield S13JDUK

Particle breakage commonly occurs during processing of particulate materials,but a mechanistic model of particle impact breakage is not fully *** article presents oblique impact breakage characteristics of nonspherical particles using discrete element method(DEM)*** different particle shapes,***,cuboidal and cylindrical,are *** spheres are agglomerated with bridging bonds to model the breakage characteristics under impact *** effect of agglomerate shapes on the breakage pattern,damage ratio,and fragment size distribution is fully *** using a newly proposed oblique impact model,unified breakage master surfaces are theoretically constructed for all the particle shapes under oblique impact *** developed approach can be applied to modelling particulate processes where nonspherical particles and oblique impact breakage are prevailing.

关键词： Breakage master curve Nonspherical particle Oblique impact Equivalent velocity Discrete element method(DEM) Bonded contact model

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Novel elastomeric spiropyran‑doped poly(dimethylsiloxane)optical waveguide for UV sensing

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Frontiers of Optoelectronics 2024年第3期17卷 1-15页

作者： Camila Aparecida Zimmermann Kof Novignon Amouzou Dipankar Sengupta Aashutosh Kumar Nicole Raymonde Demarquette Bora Ung department of Electrical {1. École de Technologie SupérieureMontrealQC H3C 1K3Canada department of Mechanical {1. École de Technologie SupérieureMontrealQC H3C 1K3Canada

Novel poly(dimethylsiloxane)(PDMS)doped with two diferent spiropyran derivatives(SP)were investigated as potential candidates for the preparation of elastomeric waveguides with UV-dependent optical ***,free-standing flms were prepared and evaluated with respect to their photochromic response to UV ***,reversibility as well as photofatigue and refractive index of the SP-doped PDMS samples were ***,SP-doped PDMS waveguides were fabricated and tested as UV sensors by monitoring changes in the transmitted optical power of a visible laser(633 nm).UV sensing was successfully demonstrated by doping PDMS using one spiropyran derivative whose propagation loss was measured as 1.04 dB/cm at 633 nm,and sensitivity estimated at 1.5%change in transmitted optical power per unit change in UV *** decay and recovery time constants were measured at 42 and 1.7 s,respectively,with an average UV saturation dose of 0.4 J/*** prepared waveguides exhibited a reversible and consistent response even under *** sensor parameters can be tailored by varying the waveguide length up to 21.cm,and are afected by white light and temperatures up to 70℃.This work is relevant to elastomeric optics,smart optical materials,and polymer optical waveguide sensors.

关键词： Spiropyrans PDMS Photochromism Polymer optical waveguides UV detection

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