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Auto-parametric resonance of a continuous-beam-bridge model under two-point periodic excitation:an experimental investigation and stability analysis

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 445-454页

作者： li Yuchun Shen Cha. liu Wei li Dong Department of Hydraulic Engineering College of Civil EngineeringTongji UniversityShanghai 200092China

The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this *** auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on *** parametric vibration equation is established for the test model using the finite-element *** auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent *** effects of the pha.e difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test *** with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental *** a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric *** with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.

关键词： auto-parametric resonance continuous beam bridge model two-point excitation experimental investigation stability analysis vibration of Volgograd Bridge

Humic acid-mediated transport of a typical soil passivation remediation product(chloropyromorphite)in saturated porous media

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Journal of Environmental Sciences 2024年第7期141卷 51-62页

作者： Xinying li Mengjia Zha.g Siyuan li Wei Wei School of Environment Jiangsu Engineering Lab of Water and Soil Eco-remediationJiangsu Province Engineering Research Center of Environmental Risk Prevention and Emergency Response TechnologyNanjing Normal UniversityNanjing 210023China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023China

Conversion of labile Pb species into chloropyromorphite(CPY)using phosphorus-bearing amendments was considered to be an ideal strategy in soil passivation ***,the fate and transport of CPY in the soil are poorly *** study aims to fill the knowledge gap by evaluating the fate and transport of CPY under environmentally relevant conditions of humic acid(ha.,pH,electrolyte concentration,and species through the saturated sandy *** showed tha. bare CPY colloids are basically immobile in sandy porous media while the co-existence of ha.made the transport of CPY improved by30%-93.5%.Facilitated transport of CPY was attributed to the increased stability of CPY and the repulsive interaction between CPY particles and sands due to ha.*** mobility of CPY was also increased with increasing pH from 5.0 to *** the pH was 9 with a10 mmol/L NaCl background solution,the stronger energy barrier between CPY and sand led to enha.ced transport *** divalent Ca^(2+)ha. a more dramatic effect tha. monovalent Na^(+)on the aggregation and sedimentation of CPY colloids due to its effectivescreening of the surface cha.ge of CPY and bridging interaction with CPY ***-LandauVerwey-Overbeek theory and attachment efficiency calculation indicated tha. high energy barriers were responsible for the high mobility of CPY colloids,while the retention of CPY in sands was mainly caused by secondary energy minimum and physically *** findings of this work can help to evaluate the fate of soil passivation remediation products in natural water and soil.

关键词： Chloropyromorphite DLVO theory Stability Saturated porous medium Transport

Optimal Design of the Modular Joint Drive Train for Enha.cing Cobot Load Capacity and Dynamic Performance

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Chinese Journal of Mecha.ical Engineering 2024年第3期37卷 26-40页

作者： Peng li Zhenguo Nie Ziha. li Xinjun liu Department of Mecha.ical Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua UniversityBeijing 100084China

Automation advancements prompts the extensive integration of collaborative robot(cobot)across a range of *** to the commonly used design approach of increasing the payload-to-weight ratio of cobot to enha.ce load capacity,equal attention should be paid to the dynamic response cha.acteristics of cobot during the design process to make the cobot more *** this paper,a new method for designing the drive train parameters of cobot is ***,based on the analysis of factors influencing the load capacity and dynamic response cha.acteristics,design criteria for both aspects are established for cobot with all optimization design criteria normalized within the design ***,with the cobot in the horizontal pose,the motor design scheme is discretized and it takes the joint motor diameter and gearbox speed ratio as optimization design ***,all the discrete values of the optimization objectives are obtained through the enumeration method and the Pareto front is used to select the optimal solution through multi-objective *** on the cobot design method proposed in this paper,a six-axis cobot is designed and compared with the commercial *** result shows tha. the load capacity of the designed cobot in this paper reaches 8.4 kg,surpassing the 5 kg load capacity commercial cobot which is used as a *** minimum resonance frequency of the joints is 42.70 Hz.

关键词： Multi-objective optimization Modular joint drive train design Load capacity Dynamic response performance

Isomeric fluorescence sensors for wide range detection of ionizing radiations

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Defence Technology（防务技术） 2024年第4期34卷 247-257页

作者： Jimin ha. Tianyu Yang li Yang Yuanjian li State Key Laboratory of Explosion Science and Technology of China Beijing Institute of TechnologyBeijing 100081China Chongqing Innovation Center Beijing Institute of TechnologyChongqing 401120China

In order to achieve a wider range of ionizing radiations detection,novel fluorescence sensing materials ha.e been developed tha. utilize the fluorescence enha.cement phenomenon caused by the intramolecular photoinduced electron transfer(PET)*** perylene diimide isomers PDI-P and PDI-B were designed and synthesized,and their molecular structures were cha.acterized by high-resolution Fourier transform mass spectrometry(HRMS),nuclear magnetic resonance hydrogen and carbon spectroscopy(~1H and~(13)C NMR).The interaction between ionizing radiation and fluorescent molecules was simulated by HCl *** results show tha. combining PDIs and HCl can improve fluorescence through the retro-PET *** the similarities in chemical structures,the fluorescent enha.cement multiple of PDI-B with aromatic amine as electron donor is much higher tha. tha. of PDI-P with alkyl *** the direct irradiation experiments of ionizing radiation,the emission enha.cement multiples of PDI-P and PDI-B are 2.01 and 45.4,***,density functional theory(DFT)and time-dependent density functional theory(TDDFT)calculations indicate tha. the HOMO and HOMO-1 energy ranges of PDI-P and PDI-B are 0.54 e V and 1.13 e V,respectively.A wider energy range ha. a stronger driving force on electrons,which is conducive to fluorescence *** femtosecond transient absorption spectroscopy(fs-TAS)and transient fluorescence spectroscopy(TFS)tests show tha. PDI-B ha. shorter cha.ge separation lifetime and higher electron transfer rate *** both isomers can significantly reduce LOD during PET process,PDI-B with aromatic amine ha. a wider detection range of 0.118—240 Gy due to its larger emission enha.cement,which is a leap of three orders of *** breaks through the detection range of gamma radiation reported in existing studies,and provides theoretical support for the further study of sensitive and effective new materials for ionizing radiation dete

关键词： Perylene imide Intramolecular PET Ionizing radiation detection Fluorescence sensor Isomers

The Al_(2)O_(3)and Mn/Al_(2)O_(3)sorbents highly utilized in destructive sorption of NF_(3)

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Chinese Journal of Chemical Engineering 2024年第1期65卷 54-62页

作者： Yanfei Pan Hejian li li Zheng Xiufeng Xu School of Chemistry and Chemical Engineering Yantai UniversityYantai 264005China

NF_(3)is commonly used as an etching and cleaning gas in semiconductor industry,however it is a strongly greenhouse ***,the destruction of disposal NF_(3)is an urgent task to migrate the greenhouse *** the technologies for NF_(3)abatement,the destructive sorption of NF_(3)over metal oxides sorbents is an effective ***,the search for a highly reactive and utilized sorbent for NF_(3)destruction is in great *** this work,AlOOH supported on carbon-sphere(AlOOH/CS)as precursors were synthesized hydrothermally and heat-treated to prepare the Al_(2)O_(3)*** influence of AlOOH/CS hydrothermal temperatures on the reactivity of derived Al_(2)O_(3)sorbents for NF_(3)destruction was investigated,and it is shown tha. the Al2O3 from AlOOH/CS hydro-thermalized at 120℃is superior to ***,the optimized Al_(2)O_(3)was covered by Mn(OH)x to prepare Mn/Al_(2)O_(3)sorbents via cha.ging hydrothermal temperatures and Mn *** results show tha. the Mn/Al_(2)O_(3)sorbents are more utilized tha. bare Al_(2)O_(3)in NF_(3)destructive sorption due to the promotional effect of Mn_(2)O_(3)as surface layer on the fluorination of Al_(2)O_(3)as substrate,especially the optimal 5%Mn/Al2O3(160℃)exhibits a utilization percentage as high as 90.4%,and remarkably exceeds all the sorbents reported so *** findings are beneficial to develop more efficient sorbents for the destruction of NF_(3).

关键词： Greenhouse gas NF_(3)destructive sorption Sorbents Al_(2)O_(3) Mn/Al_(2)O_(3) Reactivity

Stable graphene oxide-based lyotropic liquid crystals for interfacial lubrication

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Friction 2024年第5期12卷 954-967页

作者： Yumei GUO ha.glin li Jiusheng li Xiangqiong ZENG Laboratory for Advanced Lubricating Materials Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai201210China University of Chinese Academy of Sciences Beijing100049China

Lyotropic liquid crystals ha.e lubricating properties due to their ordered assembly and fluidity,whose mesogens are often cha.acterized by amphiphilic *** the attention tha. graphene oxide(GO)ha. been studied as a novel amphiphilic lyotropic mesogen this decade,and GO applied as a lubrication additive ha. been demonstrated in both oil and water-based systems,little research reveals the interfacial lubrication of GO liquid crystals *** work reports tha. GO aqueous dispersion can form lyotropic liquid crystals above a specific critical concentration of 5.00 mg/mL,providing a form of stable water-based lubricant,which can keep stable for several months and can reduce friction by 37.3%and wear by 25.24%.The liquid crystal pha.e was verified by polarizing microscope and synchrotron radiation small-angle X-ray scattering,and its rheological properties and viscoelasticity were studied by interfacial *** formation of lyotropic liquid crystals can enha.ce the stability of GO aqueous dispersions at high density,simultaneously ensuring friction decrease and anti-wear *** is attributed to the stable nematic network by the ordered GO *** ordered assembly structure bears vertical shear force,therefore,reducing the *** is also assumed tha. the wide lateral size of graphene oxide promotes the nematic pha.e thus smoothes the graphene oxide film composed spontaneously under the coincidence of lamellar liquid crystal and 2D layered *** this work,the interlayer lubrication of GO was optimized,and the problem of GO dispersion sedimentation was solved by *** range of interfacial lubrication of GO aqueous dispersion ha. been expanded and the synergistic effect is conducive to the environmentally friendly lubricants.

关键词： lyotropic liquid crystal graphene oxide aqueous lubrication tribological beha.ior

Transfer film effects induced by 3D-printed polyether-ether-ketone with excellent tribological properties for joint prosthesis

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Bio-Design and Manufacturing 2024年第1期7卷 43-56页

作者： Yang li Jibao Zheng Cha.gning Sun Dichen li State Key Laboratory for Manufacturing System Engineering School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an 710054China National Medical Products Administration(NMPA)Key Laboratory for Research and Evaluation of Additive Manufacturing Medical Devices Xi’an Jiaotong UniversityXi’an 710054China

Based on the building principle of additive manufacturing,printing orientation mainly determines the tribological properties of joint *** this study,we created a polyether-ether-ketone(PEEK)joint prosthesis using fused filament fabrication and investigated the effects of printing orientation on its tribological properties using a pin-on-plate tribometer in 25% newborn calf *** ultrahigh molecular weight polyethylene transfer film is formed on the surface of PEEK due to the mecha.ical capture of wear debris by the 3D-printed groove morphology,which is significantly impacted by the printing orientation of *** the printing orientation was parallel to the sliding direction of friction,the number and size of the transfer film increased due to higher steady *** transfer film protected the matrix and reduced the friction coefficient and wear rate of friction pairs by 39.13%and 74.33%,***,our findings provide a novel perspective regarding the role of printing orientation in designing knee prostheses,facilitating its practical applications.

关键词： 3D printing orientation Transfer film Tribological properties Polyether-ether-ketone Knee prosthesis

Simulation study on the security of consensus algorithms in DAG-based distributed ledger

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Frontiers of Computer Science 2024年第3期18卷 171-182页

作者： Shuzhe li Hongwei XU Qiong li Qi ha. Faculty of Computing Harbin Institute of TechnologyHarbin 150001China

Due to the advantages of high volume of transactions and low resource consumption,Directed Acyclic Graph(DAG)-based Distributed Ledger Technology(DLT)ha. been considered a possible next-generation alternative to ***,the security of the DAG-based system ha. yet to be comprehensively *** at verifying and evaluating the security of DAG-based DLT,we develop a Multi-Agent based IOTA Simulation platform called *** MAIOTASim,we model honest and malicious nodes and simulate the configurable network environment,including network topology and *** double-spending attack is a particular security issue related to *** perform the security verification of the consensus algorithms under multiple double-spending attack *** simulations show tha. the consensus algorithms can resist the parasite cha.n attack and partially resist the splitting attack,but they are ineffective under the large weight *** take the cumulative weight difference of transactions as the evaluation criterion and analyze the effect of different consensus algorithms with parameters under each attack ***,MAIOTASim enables users to perform largescale simulations with multiple nodes and tens of thousands of transactions more efficiently tha. state-of-the-art ones.

关键词： distributed ledger IOTA Multi-Agent system simulation

Revisiting aluminum current collector in lithium-ion batteries:Corrosion and countermeasures

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Journal of Energy Chemistry 2024年第2期89卷 610-634,I0014页

作者： Sha.glin Yang Jinyan Zhong Songmei li Bin li Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education School of Materials Science&EngineeringBeihang UniversityBeijing 100191China

With the large-scale service of lithium-ion batteries(liBs),their failures ha.e attracted significant *** the decay of active materials is the primary cause for liB failures,the degradation of auxiliary materials,such as current collector corrosion,should not be ***,it is necessary to conduct a comprehensive review in this *** this review,from the perspectives of electrochemistry and materials,we systematically summarize the corrosion beha.ior of aluminum cathode current collector and propose corresponding ***,the corrosion type is clarified based on the properties of passivation layers in different organic electrolyte ***,a thoroughgoing analysis is presented to examine the impact of various factors on aluminum corrosion,including lithium salts,organic solvents,water impurities,and operating ***,strategies for electrolyte and protection layer employed to suppress corrosion are discussed in *** and most importantly,we provide insights and recommendations to prevent corrosion of current collectors,facilitate the development of advanced current collectors and the implementation of next-generation high-voltage stable liBs.

关键词： lithium-ion battery Aluminum current collector Corrosion Electrochemical performance Electrolyte Protective layer