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Isomeric fluorescence sensors for wide range detection of ionizing radiations

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

作者： Jimin Han 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 have been developed that utilize the fluorescence enhancement 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 characterized 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 that combining PDIs and HCl can improve fluorescence through the retro-PET *** the similarities in chemical structures,the fluorescent enhancement multiple of PDI-B with aromatic amine as electron donor is much higher than that of PDI-P with alkyl *** the direct irradiation experiments of ionizing radiation,the emission enhancement 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 that 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 has a stronger driving force on electrons,which is conducive to fluorescence *** femtosecond transient absorption spectroscopy(fs-TAS)and transient fluorescence spectroscopy(TFS)tests show that PDI-B has shorter charge separation lifetime and higher electron transfer rate *** both isomers can significantly reduce LOD during PET process,PDI-B with aromatic amine has a wider detection range of 0.118—240 Gy due to its larger emission enhancement,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

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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 that 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 changing hydrothermal temperatures and Mn *** results show that the Mn/Al_(2)O_(3)sorbents are more utilized than 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

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Plastic deformation behavior of a Cu-10Ta alloy under strong impact loading

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Defence Technology（防务技术） 2024年第2期32卷 368-382页

作者： Ping Song Jianghai liu Wenbin li Yiming li Research Institute of Chemical Defense Academy of Military ScienceBeijing102205China Ministerial Key Laboratory of ZNDY Nanjing University of Science and TechnologyNanjing210094China

In this work,a Cu-10Ta alloy with a copper to tantalum mass ratio of 9:1 is prepared using powder metallurgy *** properties of the alloy,including density,microstructure,melting point,and constant-volume specific heat,are *** the split Hopkinson pressure bar(SHPB)and flyerplate impact experiments,the relationship between equivalent stress and equivalent plastic strain of the material is studied at temperatures of 298-823 K and under strain rates of 1×10^(-3)-5.2×10^(3)s^(-1),and the Hugoniot relationship at impact pressures of 1.46-17.25 GPa and impact velocities of 108-942 m/s is *** of the Cu-10Ta microstructure that occurs during high-strain-rate impact is *** indicate that the Cu-10Ta alloy possesses good thermal stability,and at ambient temperatures of up to 50%its melting point,stress softening of less than 15%of the initial strength is observed.A modified J-C constitutive model is employed to accurately predict the variation of yield strength with strain *** strong impact,the copper phase is identified as the primary source of plastic deformation in the Cu-10Ta alloy,while significant deformation of the high-strength tantalum particles is less ***,the longitudinal wave speed D is found to correlate linearly with the particle velocity u upon strong *** reveals that the sound speed and spallation strength of the alloy increase with increasing impact pressure.

关键词： Cu-10Ta SHPB Plastic deformation Flyer impact Hugoniot relationship

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Design optimization of a hexapod vibration isolation system for electro-optical payload

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Chinese Journal of Aeronautics 2024年第2期37卷 330-342页

作者： Jing li Weipeng li Xiaoyan ZHANG Hai HUANG School of Astronautics Beihang UniversityBeijing 100191China

The electro-optical payloads on mobile platforms generally suffer undesirable vibrations generated by maneuvers and *** vibrations are in six degrees of freedom and cause line-of-sight jitters,resulting in image blurring and loss of tracking *** this paper,a Hexapod Vibration Isolation System(HVIS)is proposed and optimized to solve this *** optimization aims to centralize and minimize the natural frequencies of HVIS,for expanding the vibration isolation bandwidth and improving the vibration isolation in the higher frequency *** that the design space for HVIS is limited and interfered with the frames of the mobile platform,a non-collision algorithm is proposed and applied in the optimization to obtain the feasible optimal *** optimization result shows that the natural frequency bandwidth has been reduced by 42.9%,and the maximum natural frequency is reduced by 30.2%.The prototypes of initial and optimal designs are manufactured and *** simulated and experimental results demonstrate the validity of the optimization,and the optimal design provides a maximum of 15 dB more isolation in rotation direction than the initial design.

关键词： Electro-optical payload Vibrations Isolation system Hexapod Optimization Non-collision design

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Dynamic modeling and RBF neural network compensation control for space flexible manipulator with an underactuated hand

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Chinese Journal of Aeronautics 2024年第3期37卷 417-439页

作者： Dongyang SHANG Xiaopeng li Meng YIN Fanjie li School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China

In space operation,flexible manipulators and gripper mechanisms have been widely used because of light weight and ***,the vibration caused by slender structures in manipulators and the parameter perturbation caused by the uncertainty derived from grasping mass variation cannot be *** existence of vibration and parameter perturbation makes the rotation control of flexible manipulators difficult,which seriously affects the operation accuracy of ***’s more,the complex dynamic coupling brings great challenges to the dynamics modeling and vibration *** solve this problem,this paper takes the space flexible manipulator with an underactuated hand(SFMUH)as the research *** dynamics model considering flexibility,multiple nonlinear elements and disturbance torque is established by the assumed modal method(AMM)and Hamilton’s principle.A dynamic modeling simplification method is proposed by analyzing the nonlinear ***’s more,a sliding mode control(SMC)method combined with the radial basis function(RBF)neural network compensation is ***,the control law is designed using a saturation function in the control method to weaken the chatter *** the help of neural networks to identify the uncertainty composition in the SFMUH,the tracking accuracy is *** results of ground control experiments verify the advantages of the control method for vibration suppression of the SFMUH.

关键词： Space flexible manipulator RBF neural network Underactuated hand Dynamic models Model simplification

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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 Changning 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 mechanical 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

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Few-shot incremental radar target recognition framework based on scattering-topology properties

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Chinese Journal of Aeronautics 2024年第8期37卷 246-260页

作者： Chenxuan li Weigang ZHU Bakun ZHU Yonggang li Graduate School Space Engineering UniversityBeijing 101400China Department of Electronic and Optical Engineering Space Engineering UniversityBeijing 101400China

The continuous emergence of new targets in open scenarios leads to a substantial decrease in the performance of Inverse Synthetic Aperture Radar(ISAR)recognition ***,data scarcity further exacerbates the challenge of identifying new classes of ISAR *** this paper,a few-shot incremental target recognition framework based on Scattering-Topology Properties(STPIL)is ***,STPIL extracts scattering-topology properties of ISAR targets as recognition ***,the pseudo-incremental training strategy effectively alleviates the algorithm’s forgetting of old knowledge,and improves compatibility with new ***,a feature embedding network,with few parameters,is designed based on the graph neural *** embedding network is highly adaptable to changes in data ***,STPIL fully considers the joint distribution and marginal distribution in scattering features,and uses the Brownian distance metric module to make the scattering-topology features more *** results on both the simulation dataset and the public measured data indicate that STPIL can effectively balance new classes with old classes,and has superior performance to other advanced methods in the incremental recognition of targets.

关键词： Brownian distance metric Graph neural networks Incremental learning Inverse Synthetic Aperture Radar(ISAR) Scattering

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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 HAN 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)has been considered a possible next-generation alternative to ***,the security of the DAG-based system has 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 that the consensus algorithms can resist the parasite chain 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 than state-of-the-art ones.

关键词： distributed ledger IOTA Multi-Agent system simulation

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Optimal Design of the Modular Joint Drive Train for Enhancing Cobot Load Capacity and Dynamic Performance

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 26-40页

作者： Peng li Zhenguo Nie Zihao li Xinjun liu Department of Mechanical 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 enhance load capacity,equal attention should be paid to the dynamic response characteristics 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 characteristics,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 that 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

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Piezoelectric composite hydrogel with wireless electrical stimulation enhances motor functional recovery of spinal cord injury

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Journal of Materials Science & Technology 2024年第5期172卷 228-239页

作者： Zehao li Guanlin li Xinyu Wang Zheng Zhao State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Sanya Science and Education Innovation Park of Wuhan University of Technology Sanya 572000China

Electrical stimulation(ES)can restore motor function after spinal cord injury(SCI).However,traditional intraspinal ES has many disadvantages,such as the need for a complex circuitry device,an external power source,and a second surgery to remove the *** materials have received increasing at-tention due to their potential to convert ambient mechanical energy into ES without an external power source or implantation of ***,a novel polydopamine(PDA)coated barium titanate(BaTiO_(3))nanoparticles(BaTiO_(3)@PDA)incorporated silk fibroin(SF)hydrogel(SFBT)was *** SFBT hy-drogel was crosslinked by horseradish peroxidase(HRP)/hydrogel peroxide(H_(2)O_(2))to integrate the piezo-electric potency of BaTiO_(3)with the thermal sensitivity of HRP/H_(2)O_(2)for SCI *** hydrogel con-taining 5%(w/v)BaTiO_(3)@PDA nanoparticles(SFBT-5),which was selected for in vivo study,exhibited a short gelation time(5 min),suitable storage modulus(925±35 Pa),and wireless ES(average current of 124 nA).Moreover,Basso-Beattie-Bresnahan(BBB)scores test and footprint analysis demonstrated that the SFBT-5 hydrogel successfully enhanced motor functional recovery of *** histopathological assess-ments,the SFBT-5 hydrogel significantly accelerated spinal cord healing,as indicated by smaller lesion cavities(∼16.7%of the SCI group).Meanwhile,the SFBT-5 hydrogel accelerated neurogenesis,facilitated axon regrowth and synapse formation,and promoted ***,this study highlights the potential of piezoelectric hydrogels for SCI regeneration.

关键词： Silk fibroin Barium titanate Piezoelectric hydrogel Spinal cord injury Electrical stimulation

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