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Multi-layer perceptron-based data-driven multiscale modelling of granular materials with a novel Frobenius norm-based internal variable

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2198-2218页

作者： Mengqi Wang y.T.feng Shaoheng Guan Tongming Qu Zienkiewicz Centre for Computational Engineering Faculty of Science and EngineeringSwansea UniversitySwanseaWalesSA18EPUK Institute of Theoretical and Computational physics Graz University of TechnologyGraz8010Austria Department of Civil and Environmental Engineering Hong Kong University of Science and TechnologyClearwater BayKowloonHong KongChina

One objective of developing machine learning(ML)-based material models is to integrate them with well-established numerical methods to solve boundary value problems(BVps).In the family of ML models,recurrent neural networks(RNNs)have been extensively applied to capture history-dependent constitutive responses of granular materials,but these multiple-step-based neural networks are neither sufficiently efficient nor aligned with the standard finite element method(FEM).Single-step-based neural networks like the multi-layer perceptron(MLp)are an alternative to bypass the above issues but have to introduce some internal variables to encode complex loading *** this work,one novel Frobenius norm-based internal variable,together with the Fourier layer and residual architectureenhanced MLp model,is crafted to replicate the history-dependent constitutive features of representative volume element(RVE)for granular *** obtained ML models are then seamlessly embedded into the FEM to solve the BVp of a biaxial compression case and a rigid strip footing *** obtained solutions are comparable to results from the FEM-DEM multiscale modelling but achieve significantly improved *** results demonstrate the applicability of the proposed internal variable in enabling MLp to capture highly nonlinear constitutive responses of granular materials.

关键词： Granular materials History-dependence Multi-layer perceptron(MLp) Discrete element method FEM-DEM Machine learning

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Increasing polymer scission rate by tying an overhand knot

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Science China Chemistry 2024年第11期67卷 3498-3499页

作者： yuheng Hu Jennifer T.Ou Jim y.Huang yuanning feng Department of Chemistry and Biochemistry The University of Oklahoma

Similar to the phenomenon of knotted ropes in life, knotted climbing ropes will reduce their strength due to knots. Although computer simulations [1], theoretical speculation[2,3], and intuition [3] suggest that similar processes may occur at the nanoscale, this hypothesis has not been experimentally proven before. With the increasing maturity of molecular recognition and self-assembly, a research communication by Leigh et al. [4] published in Nature Chemistry introduced a molecular overhand knot into a polymer to study its effect on the scission rate of the polymer chain under tension.

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A particle-resolved heat-particle-fluid coupling model by DEM-IMB-LBM

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2267-2281页

作者： Ming Xia Jinlong Fu y.T.feng fengqiang Gong Jin yu Hunan Key Laboratory of Geomechanics and Engineering Safety Xiangtan UniversityXiangtan411105China Zienkiewicz Institute for Modelling Data and AISwansea UniversitySwanseaSA18EPUK School of Civil Engineering Southeast UniversityNanjing211189China Fujian Research Center for Tunneling and Urban Underground Space Engineering Huaqiao UniversityXiamen361021China

Multifield coupling is frequently encountered and also an active area of research in geotechnical *** this work,a particle-resolved direct numerical simulation(pR-DNS)technique is extended to simulate particle-fluid interaction problems involving heat transfer at the grain *** this extended technique,an immersed moving boundary(IMB)scheme is used to couple the discrete element method(DEM)and lattice Boltzmann method(LBM),while a recently proposed Dirichlet-type thermal boundary condition is also adapted to account for heat transfer between fluid phase and solid *** resulting DEM-IBM-LBM model is robust to simulate moving curved boundaries with constant temperature in thermal *** facilitate the understanding and implementation of this coupled model for non-isothermal problems,a complete list is given for the conversion of relevant physical variables to lattice ***,benchmark tests,including a single-particle sedimentation and a two-particle drafting-kissing-tumbling(DKT)simulation with heat transfer,are carried out to validate the accuracy of our coupled *** further investigate the role of heat transfer in particle-laden flows,two multiple-particle problems with heat transfer are *** examples demonstrate that the proposed coupling model is a promising high-resolution approach for simulating the heat-particle-fluid coupling at the grain level.

关键词： particle-fluid interaction Heat transfer Discrete element method(DEM) Lattice Boltzmann method(LBM) Dirichlet-type thermal boundary Direct numerical simulation

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The design and performance of GRD onboard the GECAM satellite

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Radiation Detection Technology and Methods 2022年第1期6卷 43-52页

作者： Z.H.An X.L.Sun D.L.Zhang S.yang X.Q.Li X.y.Wen K.Gong X.H.Liang X.J.Liu y.Q.Liu y.G.Li S.L.Xiong y.B.Xu Fan Zhang X.y.Zhao C.Cai Z.Chang G.Chen C.Chen y.y.Du p.y.feng M.Gao R.Gao D.y.Guo J.J.He D.J.Hou C.y.Li G.Li L.Li X.F.Li M.S.Li F.J.Lu H.Lu B.Meng W.X.peng F.Shi H.Wang J.Z.Wang y.S.Wang H.Z.Wang X.Wen S.Xiao y.p.Xu J.W.yang Q.B.yi S.N.Zhang C.y.Zhang C.M.Zhang Fei Zhang y.Zhao X.Zhou CAS Institute of High Energy PhysicsBeijing 100049China State Key Laboratory of particle Detection and Electronics Beijing 100049China 3 Xiangtan UniversityXiangtan 411105China 4 Beijing Normal UniversityBeijing 110875China Xiangtan University Xiangtan 411105China Beijing Normal University Beijing 110875China

Background Each GECAM satellite payload contains 25 gamma-ray detectors(GRDs),which can detect gamma-rays and particles and can roughly localize the Gamma-Ray Bursts(GRBs).GRD was designed using lanthanum bromide(LaBr3)crystal as the sensitive material with the rear end coupled with silicon photomultiplier(SipM)array for *** In aerospace engineering design of GRD,there are many key points to be *** this paper,we present the specific design scheme of GRD,the assembly and the performance test results of *** Based on Monte Carlo simulation and experimental test results,the specific schematic design and assembling process of GRD were *** being fully assembled,the GRDs were conducted performance tests by using radioactive source and also conducted random vibration *** and conclusion The test results show that all satellite-borne GRDs have energy resolutionperformance,which meets the requirement of spatial application.

关键词： Lanthanum bromide scintillator SipM array GECAM Gamma-ray detector Energy resolution

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An MpI parallel DEM-IMB-LBM framework for simulating fluid-solid interaction problems

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2219-2231页

作者： Ming Xia Liuhong Deng fengqiang Gong Tongming Qu y.T.feng Jin yu Hunan Key Laboratory of Geomechanics and Engineering Safety Xiangtan UniversityXiangtan411105China School of Civil Engineering Southeast UniversityNanjing211189China Department of Civil and Environmental Engineering Hong Kong University of Science and TechnologyHong KongChina Zienkiewicz Centre for Computational Engineering Swansea UniversitySwanseaSA18ENUK Fujian Research Center for Tunneling and Urban Underground Space Engineering Huaqiao UniversityXiamen361021China

The high-resolution DEM-IMB-LBM model can accurately describe pore-scale fluid-solid interactions,but its potential for use in geotechnical engineering analysis has not been fully unleashed due to its prohibitive computational *** overcome this limitation,a message passing interface(MpI)parallel DEM-IMB-LBM framework is proposed aimed at enhancing computation *** framework utilises a static domain decomposition scheme,with the entire computation domain being decomposed into multiple subdomains according to predefined processors.A detailed parallel strategy is employed for both contact detection and hydrodynamic force *** particular,a particle ID re-numbering scheme is proposed to handle particle transitions across sub-domain *** benchmarks are conducted to validate the accuracy and overall performance of the proposed ***,the framework is applied to simulate scenarios involving multi-particle sedimentation and submarine *** numerical examples effectively demonstrate the robustness and applicability of the MpI parallel DEM-IMB-LBM framework.

关键词： Discrete element method(DEM) Lattice Boltzmann method(LBM) Immersed moving boundary(IMB) Multi-cores parallelization Message passing interface(MpI) CpU Submarine landslides

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A novel method for AFRps burrs removal:principle of mechanochemo-induced fiber fracture

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Chinese Journal of Aeronautics 2024年第7期37卷 522-538页

作者： Jie XU Bo LI pingfa feng Qiang WANG feng feng Division of Advanced Manufacturing Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Changhe Aircraft Industry(Group)Co.Ltd Jingdezhen 333000China

Burrs generated during the machining of Aramid-Fiber-Reinforced Composites(AFRps)pose a challenge for the production efficiency of aircraft and helicopter housing *** studies have generally attempted to suppress burrs by referring to delamination suppression *** contrast to stratification,burrs are remediable machining *** such,a mechanochemical method with burrs trimming technological strategy are implemented to effectively combat ***,we clarify the mechanism by which aramid fibers cannot be cut off using analytical and numerical *** addition,the mechanism of fiber fracture with Modified polyurethane Reactive polymer(M-pUR),and development of anti-burr devices(thermostatic adhesive sealed generator)are ***,the experimental results show that the reduction rate in burr length is 87%-91%through the mechanochemical *** method not only opens a new avenue to solve the burr problem of aramid fibers but also builds an interdisciplinary bridge between polymer science and composite machining.

关键词： Mechanochemical method Burrs Orthogonal cutting Aramid fiber-reinforced composites Milling

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Editorial for Multiscale&Multifield Coupling in Geomechanics

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 1919-1921页

作者： Min Wang pengzhi pan Andrew H.C.Chan y.T.feng T-3 Fluid Dynamics and Solid Mechanics Theoretical DivisionLos Alamos National LaboratoryNew MexicoUSA Institute of Rock and Soil Mechanics Chinese Academy of SciencesWuhanChina School of Engineering University of TasmaniaTasmaniaAustralia College of Engineering Swansea UniversityWalesUK

We are delighted to serve as guest editors for this special issue in the Journal of Rock Mechanics and Geotechnical *** purpose of this special issue is dedicated to gathering the latest research work on Multiscale&Multifield Coupling in Geomechanics,where we delve into the intricate interplay of various fields and scales that govern the behavior of *** total,30 manuscripts from USA,China,UK,Germany,Canada,India and United Arab Emirates are selected to be included in this issue.

关键词： materials. gathering mechanics

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Mechanisms behind the environmental sensitivity of carbon fiber reinforced polytetrafluoroethylene(pTFE)

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Friction 2024年第5期12卷 997-1015页

作者： pontus JOHANSSON p.MARKLUND M.BJORLING y.SHI Division of Machine Element LuleåUniversity of TechnologyLuleåSE-97187Sweden

Carbon fiber reinforced polytetrafluoroethylene (CF/pTFE) composites are known for their exceptional tribological performance when sliding against steel or cast iron in inert gas environments. Compared to experiments in humid air, about an order of magnitude lower wear rate and several times lower coefficient of friction have been reported for tests conducted in dry nitrogen and hydrogen. Moreover, trace moisture has been shown to affect the friction and wear significantly of this tribosystem, although a possible effect of oxygen cannot be ruled out due to uncertainties regarding the oxygen concentrations. While several studies have pointed out the environmental sensitivity of CF/pTFE, the understanding of the underlying mechanisms are very limited. The objective of this research is to investigate the individual and combined effect of oxygen and moisture on the tribological behavior of CF/pTFE sliding against steel. Additionally, this study aims to elucidate the underlying mechanisms that govern the environmental sensitivity of the system. Climate-controlled three-pin-on-disc experiments were conducted in nitrogen atmospheres at various concentrations of oxygen and moisture. The tribological results clearly demonstrate that both moisture and oxygen contribute to increased friction and wear. However, the adverse effect was much more pronounced for oxygen than moisture. A qualitative method was developed to estimate the tribofilm coverage on the CF/pTFE surface. Results showed strong correlation between high coverage of strongly adhered tribofilm and low wear rate. Moreover, a loosely adhered tribofilm was observed on top of the CF/pTFE surface in presence of moisture. FTIR analysis indicated that the loosely adhered tribofilm found in the moisture-enriched environment contained a significant amount of adsorbed water, which may explain the lower coefficient of friction in presence of moisture compared to oxygen. The adsorbed water in the loosely adhered tribofilm coul

关键词： polymer composite tribofilm tribochemistry atmosphere

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Annotated survey and perspectives on rail transport energy system RAMS evaluation technology

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Green Energy and Intelligent Transportation 2024年第3期3卷 75-90页

作者： Ruifeng Shi Lingzhi Zhang feng Lin Jin Ning Limin Jia Kwang y.Lee School of Control and Computer Engineering North China Electric Power UniversityBeijing 102206China China Institute of Energy and Transportation Integrated Development Beijing 102206China State Key Lab of Rail Traffic Control&Safety Beijing Jiaotong UniversityBeijing 100044China Department of Electrical and Computer Engineering Baylor UniversityWacoTX 76798USA

The rail transit system plays a crucial role in modern *** the increasing demand for clean and green energy in the transport sector,its energy system is expected to achieve low-carbon and highly efficient energy utilization in rail ***,the gradual development of the rail transport energy system has led to an increase in its complexity,and the rising difficulty of system assessment has faced the limitations of traditional assessment ***,it is essential to develop effective assessment *** paper begins by providing a systematic review of the development status of Reliability,Availability,Maintainability and Safety(RAMS)assessment and analyzing the shortcomings of traditional RAMS assessment technology in the context of rail transit energy ***,based on the four fundamental properties of RAMS,it summarizes the current state of key assessment technologies in the field of rail ***,the paper delves into the challenges and potential solutions concerning the implementation of RAMS assessment technology for rail transit energy ***,the paper offers an outlook on the future development of RAMS assessment for rail transport energy *** comprehensively analyzing these aspects,the paper aims to contribute valuable insights into optimizing the rail transit energy system,promoting its sustainable and efficient operation in the context of clean and green energy utilization.

关键词： Integration of energy and transportation RAMS evaluation Rail transit energy system

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Record-high efficiency perovskite LEDs achieved by accelerating radiative recombination

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Science China Materials 2024年第9期67卷 3039-3040页

作者： feng Gao Department of physics Chemistry and BiologyLinköping UniversityLinköping58183Sweden

Light-emitting diodes(LEDs)have revolutionized the lighting and displays due to their superior energy *** increasing demand for more efficient and brighter thin-film LEDs in flat-panel displays and solid-state lighting applications has driven extensive research into perovskite materials,which show great promise for high brightness and efficiency.

关键词： lighting radiative high

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