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Study on moisture absorption characteristics of glass fibrereinforced epoxy resin material for composite insulators based on the 3D-Fick model

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High Voltage 2024年第4期9卷 888-901页

作者： Yuming Zhang Yunpeng Liu Sizu Hou Jianghai Geng Ping Wang hebei Provincial key laboratory of power Transmission Equipment Security Defense North China Electric Power UniversityBaodingChina hebei key laboratory of power internet of things technology BaodingChina

Long-term exposure to moisture leads to a gradual deterioration of performance and reduced service life of glass fibre-reinforced epoxy resin(GFRP)material in composite ***,it is necessary to analyse the moisture absorption characteristics of GFRP material and the evolution of damage to their internal interface *** absorption tests on GFRP rod material used in composite insulators to obtain their three-dimensional diffusion coefficients are *** force microscopy was then employed to obtain the composite material system's fibre/matrix interfacial phase ***,a finite element model incorporating representative volume elements with interfacial phases and a mesoscale transient moisture absorption finite element model for the composite material was ***,the moisture absorption characteristics of GFRP material and the evolution of damage to the interfacial phase under thermal-humidity cycling conditions were *** results showed that the diffusion coefficient along the fibre direction in GFRP material was higher than that in the perpendicular *** moisture diffusion finite element model,incorporating an anisotropic interfacial phase,fitted the anisotropic diffusion coefficients of GFRP material more *** moisture invaded the GFRP material,the mismatch stresses continuously increased during the moisture ***,the non-uniform arrangement of fibres resulted in uneven distribution of moistureinduced stresses inside the material,leading to higher mismatch stresses in areas with dense fibre arrangements in the *** high and low humidity cycles led to the development of micro-cracks,micro-porosity,and interface debonding along the fibre direction at the GFRP material interfaces,thereby affecting the anisotropic moisture absorption characteristics of the *** findings of this study provide valuable insights into the mechanisms underlying the

关键词： composite fibre moisture

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PLC for In-Vehicle Network: A DRL-Based Algorithm of Diversity Combination of OFDM Subcarriers

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Chinese Journal of Electronics 2023年第6期32卷 1245-1257页

作者： CHEN Zhixiong ZHANG Zhikun CAO Tianshu ZHOU Zhenyu School of Electrical and Electronic Engineering North China Electric Power University hebei key laboratory of power internet of things technology

For low latency communication service of vehicles, it is critical to improve the delay performance of power line communication(PLC) for in-vehicle network,which can decrease the weight and cost of the vehicle. In order to minimize the total time slots used in a transmission task, an orthogonal frequency-division multiplexing(OFDM) subcarrier diversity combination algorithm of PLC based on the deep reinforcement learning(DRL) is proposed herein. The short packet communication theory is used to develop an optimal combination model with constraints on short packet reliability, transmitting power and the amount of data. The state, action, and reward function of double deep Q-learning network(DDQN) are defined, and diversity combination for OFDM subcarriers is performed using DDQN. An adaptive power allocation algorithm based on the thresholds of error rate and the data amount is used. Simulation results show that the proposed algorithm can effectively improve the delay performance of PLC under the constraints of power and data amount.

关键词： Q-learning OFDM Simulation power line communications Reliability theory Delays Resource management

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Investigation of cavitation bubble collapse near rigid boundary by lattice Boltzmann method

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Journal of Hydrodynamics 2016年第3期28卷 442-450页

作者：单鸣雷朱昌平周曦殷澄韩庆邦 College of internet of things Engineering and Jiangsu key laboratory of power Transmission and Distribution Equipment technology Hohai University

The dynamics of the bubble collapse near a rigid boundary is a fundamental issue for the bubble collapse application and prevention. In this paper, the bubble collapse is modeled by adopting the lattice Boltzmann method （LBM） and is verified, and then the dynamic characteristics of the collapsing bubble with the second collapse is investigated. The widely used Shan-Chen model in the LBM multiphase community is modified by coupling with the Carnahan-Starling equation of state （C-S EOS） and the exact difference method （EDM） for the forcing term treatment. The simulation results of the bubble profile evolution by the LBM are in excellent agreements with the theoretical and experimental results. From the two-dimensional pressure field evolution, the dynamic characteristics of the different parts during the bubble collapse stage are studied. The role of the second collapse in the rigid boundary damage is discussed, and the impeding effect between two collapses is demonstrated.

关键词： cavitation mechanics lattice Boltzmarm method bubble collapse rigid boundary

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IRS-Aided SWIPT Systems with power Splitting and Artificial Noise

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China Communications 2022年第4期19卷 108-120页

作者： Baogang Li Fuqiang Si Dongsheng Han Wujing Wu Department of Electronic and Communication Engineering North China Electric Power UniversityBaoding 071003HebeiChina hebei key laboratory of power internet of things technology North China Electric Power UniversityBaoding 071003HebeiChina

Intelligent reflecting surface(IRS) is regarded as a promising technology because it can achieve higher passive beamforming gain. In particular, the IRS assisted simultaneous wireless information and power transfer(SWIPT) system can make the information decoding receivers(IDRs) have a higher signal-to-noise ratio(SNR), and the energy harvesting receivers(EHRs) have the guarantee of minimum harvested energy threshold. Motivated by the above,in this paper, we use the power splitting(PS) at the user and introduce artificial noise(AN) into the access point(AP), so that the user in system can harvest energy and decode information simultaneously,further improve the security of user. We jointly optimize the beamforming matrix at AP, the reflection phase shift at IRS and the PS ratio, in order to maximize the user’s achievable secrecy rate, subject to the user’s minimum harvested energy threshold and AP’s transmission power. Due to the introduction of PS ratio, the coupling between variables is increased,and the complexity of the problem is significantly increased. Furthermore, the problem is non-convex, so we propose an efficient algorithm based on Taylor Formula, semi-definite relaxation(SDR) and alternating optimization(AO) to get the solution. Numerical results show that the proposed IRS-SWIPT system with PS and AN achieves significant performance improvement compared with other benchmark scheme.

关键词： intelligent reflecting surface(IRS) passive beamforming power splitting SWIPT

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Pseudopotential multi-relaxation-time lattice Boltzmann model for cavitation bubble collapse with high density ratio

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Chinese Physics B 2016年第10期25卷 189-196页

作者：单鸣雷朱昌平姚澄殷澄蒋小燕 College of internet of things Engineering Hohai University Jiangsu key laboratory of power Transmission and Distribution Equipment technology Hohai University

The dynamics of the cavitation bubble collapse is a fundamental issue for the bubble collapse application and prevention. In the present work, the modified forcing scheme for the pseudopotential multi-relaxation-time lattice Boltzmann model developed by Li Q et al. [ Li Q, Luo K H and Li X J 2013 Phys. Rev. E 87 053301] is adopted to develop a cavitation bubble collapse model. In the respects of coexistence curves and Laplace law verification, the improved pseudopotential multi-relaxation-time lattice Boltzmann model is investigated. It is found that the thermodynamic consistency and surface tension are independent of kinematic viscosity. By homogeneous and heterogeneous cavitation simulation, the ability of the present model to describe the cavitation bubble development as well as the cavitation inception is verified. The bubble collapse between two parallel walls is simulated. The dynamic process of a collapsing bubble is consistent with the results from experiments and simulations by other numerical methods. It is demonstrated that the present pseudopotential multirelaxation-time lattice Boltzmann model is applicable and efficient, and the lattice Boltzmann method is an alternative tool for collapsing bubble modeling.

关键词： lattice Boltzmann method pseudopotential model bubble collapse improved forcing scheme

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Deep Reinforcement Learning-Based URLLC-Aware Task Offloading in Collaborative Vehicular Networks

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China Communications 2021年第7期18卷 134-146页

作者： Chao Pan Zhao Wang Zhenyu Zhou Xincheng Ren hebei key laboratory of power internet of things technology North China Electric Power UniversityBeijing102206Baoding071003HebeiChina Shaanxi key laboratory of Intelligent Processing for Big Energy Data Yanan UniversityYanan 716000China

Collaborative vehicular networks is a key enabler to meet the stringent ultra-reliable and lowlatency communications(URLLC)requirements.A user vehicle(UV)dynamically optimizes task offloading by exploiting its collaborations with edge servers and vehicular fog servers(VFSs).However,the optimization of task offloading in highly dynamic collaborative vehicular networks faces several challenges such as URLLC guaranteeing,incomplete information,and dimensionality *** this paper,we first characterize URLLC in terms of queuing delay bound violation and high-order statistics of excess ***,a Deep Reinforcement lEarning-based URLLCAware task offloading algorithM named DREAM is proposed to maximize the throughput of the UVs while satisfying the URLLC constraints in a besteffort *** with existing task offloading algorithms,DREAM achieves superior performance in throughput,queuing delay,and URLLC.

关键词： collaborative vehicular networks task of-floading URLLC awareness deep Q-learning

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Adaptive Learning-Based Delay-Sensitive and Secure Edge-End Collaboration for Multi-Mode Low-Carbon power IoT

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China Communications 2022年第7期19卷 324-336页

作者： Haijun Liao Zehan Jia Ruiqiuyu Wang Zhenyu Zhou Fei Wang Dongsheng Han Guangyuan Xu Zhenti Wang Yan Qin hebei key laboratory of power internet of things technology North China Electric Power UniversityBaoding 071003HebeiChina State Grid Anhui Electric power Company Chuzhou power Supply Company Chuzhou 239000AnhuiChina

Multi-mode power internet of things(PIoT)combines various communication media to provide spatio-temporal coverage for low-carbon operation in smart ***-end collaboration is feasible to achieve the full utilization of heterogeneous resources and ***,edge-end collaboration-based multi-mode PIoT faces challenges of mutual contradiction in communication and security quality of service(QoS)guarantee,inadaptability of resource management,and multi-mode access *** propose an Adaptive learning based delAysensitive and seCure Edge-End Collaboration algorithm(ACE_(2))to optimize multi-mode channel selection and split device power into artificial noise(AN)transmission and data transmission for secure data ***_(2) can achieve multi-attribute QoS guarantee,adaptive resource management and security enhancement,and access conflict elimination with the combined power of deep actor-critic(DAC),“win or learn fast(WoLF)”mechanism,and edge-end *** demonstrate its superior performance in queuing delay,energy consumption,secrecy capacity,and adaptability to differentiated low-carbon services.

关键词： multi-mode low-carbon PIoT edge-end collaboration multi-attribute QoS guarantee security enhancement adaptive deep actor-critic

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Study on the influence mechanism of ambient humidity on the temperature rise of decay-like composite insulators

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High Voltage 2022年第5期7卷 916-924页

作者： Zheng Zhong Yuan Chen Yunpeng Liu Sizu Hou Jianghai Geng hebei key laboratory of power Transmission Equipment Security Defense North China Electric Power UniversityBaodingChina High Voltage technology Institute North China Electric Power Research InstituteBeijingChina hebei key laboratory of power internet of things technology North China Electric Power UniversityBaodingChina

At present,observing the temperature rise of composite insulators is an effective method for the detection of decay-like ***,ambient humidity will affect the temperature rise of composite insulators,which will cause problems in screening the decaylike composite ***,it is urgent to study the temperature rise principle of decay-like insulators and find out the influence mechanism of humidity on temperature *** this study,a four-electrode system is designed to measure the surface current,volume current and interface current of the decay-like short sample and the intact short sample under different *** the equivalent circuit models of short samples and the 500 kV full-size decay-like composite insulator are built to analyse the contribution rates of leakage conductance loss and polarisation loss to temperature *** results show that the contribution rates of the polarisation loss to the temperature rise of two samples are 35.8%and 23.6%in low humidity,while they are 98.3%and 64.4%in high *** the full-size decay-like composite insulator,the contribution rates of polarisation loss to its temperature rise in high or low humidity are more than 99%.In addition,the proportion of polarisation loss increases at first and then decreases with the increase of the length of the decay-like *** conclusions of this study provide a theoretical basis for further understanding the corresponding relationship between decaylike defects and temperature rise and improve the detection rate of decay-like insulators.

关键词： composite ambient humidity

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An MAC Layer Algorithm Based on power Line-Wireless Dual Media Channels and Multiplexing

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China Communications 2022年第10期19卷 78-91页

作者： Zhixiong Chen Leixin Zhi Peiru Chen YinCheng Qi School of Electrical and Electronic Engineering North China Electric Power UniversityBaoding 071003China hebei key laboratory of power internet of things technology North China Electric Power UniversityBaoding 071003China

Hybrid networking of power line and wireless communication can complement each other,save construction costs,improve network robustness,and has important value on the internet of things and smart *** power line and wireless dual-interface devices,a media access control(MAC)layer algorithm for hybrid communication is proposed,in which the stations can compete for two channels *** a station obtains two channels at the same time,the station will randomly select a channel for transmission to ensure fairness,and reset the counters when the transmission is *** this paper,the performance of the unsaturated traffic model and counter spatial division is considered,and the throughput under coupling conditions is ***,the simulation results show that the MAC layer algorithm based on the hybrid communication network can make full use of the advantages of the two channels,improve system throughput,and reduce transmission delay.

关键词： hybrid communication MAC layer Traffic model

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Plasma potential measurements using an emissive probe made of oxide cathode

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Chinese Physics B 2024年第4期33卷 571-577页

作者：李建泉马海杰陆文琪 Department of Electronic and Communication Engineering North China Electric Power UniversityBaoding 071003China hebei key laboratory of power internet of things technology North China Electric Power UniversityBaoding 071003China key laboratory of Materials Modification by Laser Ion and Electron BeamsSchool of PhysicsDalian University of TechnologyDalian 116024China

A novel emissive probe consisting of an oxide cathode coating is developed to achieve a low operating temperature and long service *** properties of the novel emissive probe are investigated in detail,in comparison with a traditional tungsten emissive probe,including the operating temperature,the electron emission capability and the plasma potential *** of the operating temperature and electron emission capability show that the tungsten emissive probe usually works at a temperature of 1800 K-2200 K while the oxide cathode emissive probe can function at about 1200 K-1400 *** addition,plasma potential measurements using the oxide cathode emissive probe with different techniques have been accomplished in microwave electron cyclotron resonance plasmas with different discharge *** is found that a reliable plasma potential can be obtained using the improved inflection point method and the hot probe with zero emission limit method,while the floating point method is invalid for the oxide cathode emissive probe.

关键词： emissive probe oxide cathode plasma potential filament temperature

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