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Synergistically enhanced dielectric, insulating and thermally conductive performances of sandwich PMMA based dielectric films

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Progress in Natural science:Materials International 2024年第3期34卷 591-597页

作者： Dongmei Zhang Yufan Li Yuchao Li Zhonggui Sun Hanxue Zhu Lujia Yang Yanhu Zhan Yankai Li Shi Wang Jun-Wei Zha school of Mathematical sciences Liaocheng University school of Materials science and engineering Liaocheng University State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM) Nanjing University of Posts & Telecommunications school of Chemistry and Biological engineering University of Science and Technology Beijing

A tri-layered(B-G-B) dielectric films were simply prepared by alternatively spin-coating boron nitride/polymethylmethacrylate(BN/PMMA, B) and graphene nanosheets(GNS/PMMA, G) compound solutions. The structure, morphology, thermal conductivity, and particularly the dielectric and relaxation behaviors were systematically studied. Results showed that a good exfoliation and dispersion of BN and GNS can be simply achieved through intensive mechanical compounding with PMMA in the internal mixer. The dielectric constant and breakdown strength of the obtained 1-3-1(B-G-B) sandwich composite film reached 4.3(@1 kHz) and 458.6kV/mm, being 119 % and 113 % higher than that of pure PMMA, respectively. Furthermore, the overall thermal conductivity of sandwich 1-3-1 composite increased by 112 % due to the addition of thermally conductive BN and GNS. The sandwich design strategy provided an effective way of achieving good permittivity, high insulation, and improved thermal conductivity simultaneously, showing potential applications in the miniaturization and integration of electronic devices.

关键词： Breakdown strength Composites Dielectric constant Sandwich structure Thermal conductivity

Data-driven active vibration control for helicopter with trailing-edge flaps using adaptive dynamic programming

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Chinese Journal of Aeronautics 2024年第6期37卷 151-166页

作者： Yu CHEN Qun ZONG Xiuyun ZHANG Jinna LI school of Electrical and Information engineering Tianjin UniversityTianjin 300072China school of Information and control engineering Liaoning Petrochemical UniversityFushun 113001China

The helicopter Trailing-Edge Flaps(TEFs)technology is one of the recent hot topics in morphing wing *** employing controlled deflection,TEFs can effectively reduce the vibration level of ***,designing specific vibration reduction control methods for the helicopters equipped with trailing-edge flaps is of significant practical *** paper studies the optimal control problem for helicopter-vibration systems with TEFs under the framework of adaptive dynamic programming combined with Reinforcement Learning(RL).Time-delay and disturbances,caused by complexity of helicopter dynamics,inevitably deteriorate the control performance of vibration *** solve this problem,a zero-sum game formulation with a linear quadratic form for reducing vibration of helicopter systems is presented with a virtual *** this context,an off-policy reinforcement learning algorithm is developed to determine the optimal control *** algorithm utilizes only vertical vibration load data to achieve a policy that reduces vibration,attains Nash equilibrium,and addresses disturbances while compensating for time-delay without knowledge of the dynamics of the helicopter *** effectiveness of the proposed method is demonstrated in a virtual platform.

关键词： Active control Adaptive dynamic program-ming Helicopter rotor Vibration control Zero-sum game

HTDcr:a job execution framework for high-throughput computing on supercomputers

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science China(Information sciences) 2024年第1期67卷 69-85页

作者： Jiazhi JIANG Dan HUANG Hu CHEN Yutong LU Xiangke LIAO school of Computer science and engineering Sun Yat-sen University school of Software engineering South China University of Technology

High-throughput computing(HTC) is a computing paradigm that aims to accomplish jobs by easily breaking them into smaller,independent ***,it requires a large amount of computing power for a long *** existing HTC frameworks are job-oriented without support for coscheduling with hardware architecture and task-level ***,most of the frameworks reach a limited scale,and their usability needs further ***,we present HTDcr,a job execution framework for the HTC on *** study aims to improve the throughput,task dispatching,and usability of the *** detail,the throughput optimizations include a sophisticated designed task management system,a hierarchical scheduler,and the co-optimization of the task-scheduling strategy with the application and hardware *** optimizations for usability include a programable execution workflow,mechanisms for more robust and reliable service qualities,and a fine-grained resource allocation system for the colocation of multiple *** to our evaluations,HTDcr can achieve outstanding scalability and high throughput on large-scale clusters for the HTC *** evaluate HTDcr with several microbenchmarks and real-world applications on Tianhe-2 and Sunway TaihuLight to demonstrate its effects on existing design *** instance,the task scheduling for two real-world applications integrated with the application and hardware characteristics achieves 1.7× and 1.9× speedups over the basic task-scheduling strategy.

关键词： high-throughput computing supercomputer task scheduling middleware password guessing

Stability of Gas Diffusion Flame in Laterally Confined Space

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Journal of Thermal science 2024年第6期33卷 2437-2449页

作者： WANG Xiuzhen ZHU Feng WANG Shuangfeng Key Laboratory of Microgravity Institute of MechanicsChinese Academy of Sciences school of engineering science University of Chinese Academy of Sciences

Lateral-confined coaxial jet diffusion flame is common in micro thrusters,and the specific impulse is mainly obtained through thermodynamic calculations with an assumption of fuel combustion with an equivalence ratio,regardless of the stability of the combustion ***,the flame behavior plays an important impact on the performance of a micro thruster through the varied combustion *** stability of confined coaxial jet diffusion flames with air coflow was studied by experiments and numerical ***,hydrogen,and propane were used as *** attachment,liftoff,blowout(extinction limits of lifted flame),and blowoff(extinction limits of attached flame) behaviors with the effect of confinement ratios and fuel properties were focused *** the range of the jet flow velocity in this research,the hydrogen flame is always attached to the jet exit,the flame tip goes from closed to open as the jet velocity increases,while the flame transitions from attachment to liftoff in the case of CH4 and ***,in a narrow confined space,the attached flame for both CH4 and C3H8 undergoes liftoff followed by ***,in a space with a high confinement ratio,the CH4 flame transitions directly from attachment to *** critical modified Craya-Curtet number,which is used to predict the onset of the recirculation,is determined through simulation and experiment,and the number is about *** work provides valuable data on flame stability inside a confined space and gives insights into the design of a thruster.

关键词： confined space Craya-Curtet number flame stability jet diffusion flame

Noise-tolerate and adaptive coefficient zeroing neural network for solving dynamic matrix square root

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CAAI Transactions on Intelligence Technology 2024年第1期9卷 167-177页

作者： Xiuchun Xiao Chengze Jiang Qixiang Mei Yudong Zhang school of Electronics and Information engineering Guangdong Ocean UniversityZhanjiangChina school of Cyber science and engineering Southeast UniversityNanjingChina school of Computing and Mathematical sciences University of LeicesterLeicesterUK

The solving of dynamic matrix square root(DMSR)problems is frequently encountered in many scientific and engineering *** the original zeroing neural network is powerful for solving the DMSR,it cannot vanish the influence of the noise perturbations,and its constant-coefficient design scheme cannot accelerate the convergence ***,a noise-tolerate and adaptive coefficient zeroing neural network(NTACZNN)is raised to enhance the robust noise immunity performance and accelerate the conver-gence speed ***,the global convergence and robustness of the pro-posed NTACZNN are theoretically analysed under an ideal environment and noise-perturbed ***,some illustrative simulation examples are designed and performed in order to substantiate the efficacy and advantage of the NTACZNN for the DMSR problem *** with some existing ZNNs,the proposed NTACZNN possesses advanced performance in terms of noise tolerance,solution accuracy,and convergence rate.

关键词： adaptive intelligent systems neural network real-time systems

Sensitivity analysis of modeling parameters to soot and PAHs prediction in ethylene inverse diffusion flame

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science China(Technological sciences) 2024年第2期67卷 486-498页

作者： WU BingKun LI TianJiao LIU Dong MIIT Key Laboratory of Thermal control of Electronic Equipment School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China Advanced Combustion Laboratory School of Energy and Power EngineeringNanjing University of Science and Technology Nanjing 210094China

The soot formation model based on inverse ethylene diffusion flames was performed to study the sensitivity of the soot formation process to the prediction *** effects of efficiency parameters such as soot inception,surface growth and coagulation on the simulation results were studied by using the adjustable efficiency *** addition,the reversible soot model and conjugate heat transfer(CHT)model were also introduced to explore their *** indicated that,among adjustable efficiency parameters,the nucleation efficiency had the greatest influence on the predicted soot and PAHs distributions,while the Habstraction-C2H2-addition(HACA)process and PAH adsorption surface growth efficiencies impacted *** adjustable efficiency parameters had a significant effect on the concentration of soot gaseous precursors and soot particles,but their effects on temperature,gas phase molecules,and intermediate species were not *** the nucleation efficiency increased from 2×10^(-6)to 1×10^(-4),the predicted value of the integrated soot was increased by nearly 50%,and the maximum primary particle number density and the number of aggregates were increased by an order of *** maximum concentration of BAPYR was ***,the peak temperature along the axial direction increased by only 3.5 *** the reversible soot model,the approximation results of the adjustable efficiency parameters could be modified,which showed the feasibility of the *** use of the CHT model promoted pyrolysis of the fuel below the outlet of the fuel tube,with high-temperature zones,soot zones,and PAHs zones moving towards higher flame ***,when using the reversible model and the CHT model,the maximum soot volume fraction decreased by 39%compared with the basic efficiency parameters,while the concentration of BAPYR increased by 162%,and the concentrations of gas phase species were decreased.

关键词： inverse diffusion flames soot formation soot model ethylene

Effects of dimethyl ether and ethanol additions on soot transition in ethylene counterflow diffusion flames

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science China(Technological sciences) 2024年第4期67卷 1094-1112页

作者： GUO LinGe YING YaoYao CHEN Chen ZHAO Xuan LIU Dong MIIT Key Laboratory of Thermal control of Electronic Equipment School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China Advanced Combustion Laboratory School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China

This paper investigates the effect of blending dimethyl ether(DME)and ethanol on the soot transition periods in ethylene counterflow diffusion flames by using a novel optical diagnostic *** soot critical transition point in different conditions is identified experimentally and *** kinds of flames are carried out to gain the soot critical transition point in counterflow diffusion flames by changing oxygen fraction(Xo)and changing volume flow rates of fuel and oxidizer(Qv).The red-green-blue(RGB)ratio method is used to precisely identify the soot critical transition point,and chemical kinetic simulations are performed to analyze the detailed reaction *** results show that compared to the ethylene flame,the soot critical transition point occurs at a higher Xoand a lower Qvwhen DME or ethanol is *** addition of DME and ethanol can inhibit soot formation,due to the degree of soot formation reaction being lower than the degree of the oxidation reaction in the blending flames.

关键词： optical diagnosis sooting tendency counterflow diffusion flame dimethyl ether ethanol

TransTM:A device-free method based on time-streaming multiscale transformer for human activity recognition

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Defence Technology（防务技术） 2024年第2期32卷 619-628页

作者： Yi Liu Weiqing Huang Shang Jiang Bobai Zhao Shuai Wang Siye Wang Yanfang Zhang Institute of Information engineering Chinese Academy of sciences School of Cyber SecurityUniversity of Chinese Academy of SciencesBeijingChina school of Information Management Beijing Information Science and Technology UniversityBeijingChina

RFID-based human activity recognition(HAR)attracts attention due to its convenience,noninvasiveness,and privacy *** RFID-based HAR methods use modeling,CNN,or LSTM to extract features ***,they have shortcomings:1)requiring complex hand-crafted data cleaning processes and 2)only addressing single-person activity recognition based on specific RF *** solve these problems,this paper proposes a novel device-free method based on Time-streaming Multiscale Transformer called *** model leverages the Transformer's powerful data fitting capabilities to take raw RFID RSSI data as input without ***,we propose a multiscale convolutional hybrid Transformer to capture behavioral features that recognizes singlehuman activities and human-to-human *** with existing CNN-and LSTM-based methods,the Transformer-based method has more data fitting power,generalization,and ***,using RF signals,our method achieves an excellent classification effect on human behaviorbased classification *** results on the actual RFID datasets show that this model achieves a high average recognition accuracy(99.1%).The dataset we collected for detecting RFID-based indoor human activities will be published.

关键词： Human activity recognition RFID Transformer

Self-optimized H-adsorption affinity of CuRu alloy cocatalysts towards efficient photocatalytic H_(2)evolution

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Journal of Materials science & Technology 2024年第7期174卷 168-175页

作者： Meiya Wang Ping Wang Xuefei Wang Feng Chen Huogen Yu school of Chemistry Chemical Engineering and Life Sciencesand School of Materials Science and EngineeringWuhan University of TechnologyWuhan 430070China Laboratory of Solar Fuel Faculty of Materials Science and ChemistryChina University of GeosciencesWuhan 430078China

In addition to the electron transfer,the appropriate H-adsorption affinity of active centers on the metal cocatalyst surface is quite important for high hydrogen-production activity of cocatalyst-modified *** typical Cu and Ru metal cocatalysts clearly exhibit a weak Cu-H bond and a strong Ru-H bond,respectively,resulting in limited activity for photocatalytic H_(2)*** this work,an ingenious strategy of self-optimized H-adsorption affinity in CuRu alloy cocatalyst is developed to simultaneously reinforce the Cu-H bond and weaken the Ru-H bond by the intrinsic electron transfer from Cu to Ru *** CuRu alloy nanoparticles(2-3 nm)were deposited on the TiO_(2)surface to prepare CuRu/TiO_(2)through a one-step photoreduction *** tests exhibited that the highest H_(2)-production rate of CuRu/TiO_(2)photocatalyst reached up to 5.316 mmol h^(-1)g^(-1),which was 24.80,1.86,and 2.60 times higher than that of the TiO_(2),Cu/TiO_(2),and Ru/TiO_(2),*** on the characterization results and theoretical calculations,the CuRu alloy cocatalyst exhibits excellent self-optimized H-adsorption affinity via the spontaneous electron transfer from Cu to Ru atom,which can greatly accelerate the photocatalytic H_(2)-production rate of TiO_(2).This work provides a feasible idea for the self-optimized H-adsorption affinity of metal active sites in the photocatalytic H_(2)-generation field.

关键词： TiO_(2) CuRu alloy Cocatalyst Self-optimized H-adsorption affinity Photocatalytic H_(2)generation