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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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Formation and transformation of metastable LPSO building blocks clusters in Mg-Gd-Y-Zn-Zr alloys by spinodal decomposition and heterogeneous nucleation

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Journal of Magnesium and Alloys 2024年第2期12卷 673-686页

作者： Xin Zhao Zhong Yang Jiachen Zhang Minxian Liang Liying Wang School of Materials Science and Chemical Engineering Xi’an Technological UniversityXi’an 710021China Xi’an Tianli Metal Composite Material Co.Ltd. Xi’an 710299China

To study the formation and transformation mechanism of long-period stacked ordered(LPSO)structures,a systematic atomic scale analysis was conducted for the structural evolution of long-period stacked ordered(LPSO)structures in the Mg-Gd-Y-Zn-Zr alloy annealed at 300℃~500℃.Various types of metastable LPSO building block clusters were found to exist in alloy structures at different temperatures,which precipitate during the solidification and homogenization *** stability of Zn/Y clusters is explained by the first principles of density functional *** LPSO structure is distinguished by the arrangement of its different Zn/Y enriched LPSO structural units,which comprises local fcc stacking sequences upon a tightly packed *** presence of solute atoms causes local lattice distortion,thereby enabling the rearrangement of Mg atoms in the different configurations in the local lattice,and local HCP-FCC transitions occur between Mg and Zn atoms occupying the nearest neighbor *** finding indicates that LPSO structures can generate necessary Schockley partial dislocations on specific slip surfaces,providing direct evidence of the transition from 18R to *** of the LPSO,devoid of any defects and non-coherent interfaces,was observed separately from other precipitated *** a result,the precipitation sequence of LPSO in the solidification stage was as follows:Zn/Ycluster+Mg layers→various metastable LPSO building block clusters→18R/24R LPSO;whereas the precipitation sequence of LPSO during homogenization treatment was observed to be as follows:18R LPSO→various metastable LPSO building block clusters→14H *** these,14H LPSO was found to be the most thermodynamically stable structure.

关键词： LPSO Spinodal decomposition Homogenization treatment Clusters Phase transformation

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Research on the variation of dielectric properties of oil-paper insulation for power equipment over a wide temperature range

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High Voltage 2024年第3期9卷 648-658页

作者： Mingze Zhang Muhe Yu Wen Zhou Yilin Liang Shengjie Lei Yunbo Shi Limin Qu Key Laboratory of Engineering Dielectrics and Its Application Ministry of Education Harbin University of Science and TechnologyHarbinChina School of Measurement and Communication Engineering Harbin University of Science and TechnologyHarbinChina Electric Power Research Institute State Grid Heilongjiang Electric Power Company LimitedHarbinChina

The main part of oil-immersed power equipment is oil-paper *** lower ambient temperatures,transformer oil will become *** a result,compared to those at room temperature or operating temperature,the frequency domain dielectric properties of oil-paper insulation at low temperatures are drastically *** evaluating the insulation condition of electrical equipment,it is essential to accurately determine their dielectric *** paper described the FDS test,the DC conductivity test,and the transformer oil viscosity test,which was carried out in a laboratory environment for different ageing of oil-immersed pressboard and transformer oil at 233–373 *** ef-fects of temperature on the dielectric properties at the competing mechanisms of polarisation and conductivity loss were clarified based on variations of the FDS *** the viscosity change of ageing transformer oil at low temperatures,the Arrhenius and VFT viscosity equations were used to achieve a fitting calculation in the different temperature *** on the molecular/ion transition model in the force field and electric field,the characterisation relationships between the dynamic viscosity,DC conductivity,and test temperature of transformer oil were *** limita-tions of conventional transformer oil equivalent dielectric relaxation models over a wide temperature range were finally clarified by combining the test findings of the DC con-ductivity over a wide temperature range with observed and simulated *** paper provides an essential theoretical reference when using the FDS test to diagnose the insulation performance of oil-immersed power equipment in extremely cold regions.

关键词： insulation viscosity immersed

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Radiative heat transfer analysis of a concave porous fin under the local thermal non-equilibrium condition:application of the clique polynomial method and physics-informed neural networks

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1613-1632页

作者： K.CHANDAN K.KARTHIK K.V.NAGARAJA B.C.PRASANNAKUMARA R.S.VARUN KUMAR T.MUHAMMAD Amrita School of Artificial Intelligence Amrita Vishwa VidyapeethamBengaluru 560035KarnatakaIndia Department of Studies in Mathematics Davangere UniversityDavangere 577002KarnatakaIndia Computational Science Lab Amrita School of EngineeringAmrita Vishwa VidyapeethamBengaluru 560035KarnatakaIndia Department of Pure and Applied Mathematics School of Mathematical SciencesSunway UniversityPetaling Jaya 47500Malaysia Department of Mathematics College of ScienceKing Khalid UniversityAbha 61413Saudi Arabia

The heat transfer through a concave permeable fin is analyzed by the local thermal non-equilibrium(LTNE)*** governing dimensional temperature equations for the solid and fluid phases of the porous extended surface are modeled,and then are nondimensionalized by suitable dimensionless ***,the obtained nondimensional equations are solved by the clique polynomial method(CPM).The effects of several dimensionless parameters on the fin's thermal profiles are shown by graphical ***,the current study implements deep neural structures to solve physics-governed coupled equations,and the best-suited hyperparameters are attained by comparison with various network *** results of the CPM and physicsinformed neural network(PINN)exhibit good agreement,signifying that both methods effectively solve the thermal modeling problem.

关键词： heat transfer fin porous fin local thermal non-equilibrium(LTNE)model physics-informed neural network(PINN)

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A Eulerian population balance/Monte Carlo approach for simulating laminar aluminum dust flames

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Particuology 2024年第5期88卷 323-343页

作者： Fabian Sewerin Jannis Finke Emmy Noether Group for Dispersed Multiphase Flows Chair of Mechanical Process EngineeringOtto-von-Guericke-Universität MagdeburgUniversitätsplatz 239106 MagdeburgGermany

Recently,metal powders have been conceptualized as carbon-free recyclable energy carriers that may form a cornerstone of a sustainable energy *** combustion of metal dusts in oxidizing atmospheres is exothermal and yields oxide particles that could,potentially,be retrieved and,subsequently,recharged by conversion to pure metals using green primary energy *** a step towards a predictive tool for designing metal dust combustors,we present a fully Eulerian modelling approach for laminar particle-laden reactive flows that is,conceptually,based on a population balance description of the dispersed particles and relies on a stochastic Eulerian solution *** the population balance equation(PBE)is formulated for the number-weighted distribution of characteristic properties among all particles near a spatial location,it is kinetically informed by the rates at which mass,momentum and heat are exchanged between the carrier gas and the particulate phase on the single particle *** the scope of the Eulerian Monte Carlo solution scheme,the property distribution is discretely represented in terms of the total number density and a finite number of property samples and the computational work is channelled towards the Eulerian estimation of mean particle *** the case of reactive aluminum particles,we combine a kinetic description of the gas-particle heat and mass transfer with a transport-limited continuum formulation to obtain rate expressions that are valid across the entire particle size range from the free molecular through the continuum *** velocity,the particle properties include only the particle mass,temperature and oxide mass *** set of thermochemical degrees of freedom is retained also as phase transitions due to melting occur,drawing on a smooth blend of the solid and liquid thermodynamic and material *** particle-level formulation encompasses aluminum evaporation,surface oxidation,scavenging of oxi

关键词： Metal dust combustion Aluminum Population balance Eulerian Monte Carlo

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Recent progress in two-dimensional metallenes and their potential application as electrocatalyst

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Journal of Energy Chemistry 2024年第7期94卷 577-598页

作者： Umer Shahzad Mohsin Saeed Muhammad Fazle Rabbee Hadi M.Marwani Jehan Y.Al-Humaidi Muhammad Altaf Raed H.Althomali Kwang-Hyun Baek Md.Rabiul Awual Mohammed M.Rahman Department of Chemistry Faculty of ScienceKing Abdulaziz UniversityJeddah 21589Saudi Arabia Department of Biotechnology Yeungnam UniversityGyeongsanSouth Korea Center of Excellence for Advanced Materials Research(CEAMR) King Abdulaziz UniversityJeddah 21589Saudi Arabia Department of Chemistry College of SciencePrincess Nourah Bint Abdulrahman UniversityP.O.BOX 84428Riyadh 11671Saudi Arabia Department of Chemistry Center of Excellence for Innovation in Chemistry(PERCH-CIC)Center of Excellence in Materials Science and TechnologyFaculty of ScienceChiang Mai UniversityChiang Mai 50200Thailand Department of Chemistry College of Art and SciencePrince Sattam Bin Abdulaziz UniversityWadi Al-Dawasir 11991Saudi Arabia Western Australian School of Mines:Minerals Energy and Chemical EngineeringCurtin UniversityGPO Box U 1987PerthWA 6845Australia

In this article,we looked at metallenes,a novel class of two-dimensional(2D)metals that are attracting interest in the energy and catalysis *** is one area where their exceptional physicochemical and electrical characteristics might be *** are unique because they include several metal atoms that are not in a coordinated *** makes them more active and improves their atomic uti-lization,which in turn increases their catalytic *** article delves into the potential of two-dimensional metals as electrocatalysts for carbon dioxide reduction,fuel oxidation,oxygen evolution,and oxygen reduction reactions in the context of sustainable energy *** to the exception-ally high surface-to-volume ratio,large surface area as well as their optimized atomic use efficiency,2D materials defined by atomic layers are crucial for surface-related sustainable energy *** to its exceptional properties,such as high conductivity and the ability to enhance the exposure of active metal sites,2D metallenes have recently attracted a lot of interest for use in catalysis,electronics,and energy-related *** their highly mobility,adjustable surface states,and electrical struc-tures that can be fine-tuned,2D metallenes are promising nanostructure materials for use in energy con-version with the sustainable applications.

关键词： Metallenes Electrocatalysts Electrochemical processes Atomically thin structure

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Theoretical assessment of discharge effects on the decomposition tendency of C_(6)F_(12)O over metallic surfaces

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High Voltage 2024年第4期9卷 862-869页

作者： Zhaolun Cui Yanpeng Hao Shuangshuang Tian Xiaoxing Zhang Yashuang Zheng School of Electric Power Engineering South China University of TechnologyGuangzhouChina State Key Laboratory of Power Transmission Equipment Technology(Chongqing University) ChongqingChina School of Electrical and Electronic Engineering Hubei University of TechnologyWuhanChina

C_(6)F_(12)O is proposed to be one potential eco-friendly insulation gas to replace ***,the assessment of its decomposition properties and the compatibility with metal electrodes in discharge faults is still challenging,which greatly hinders the development of its insulation and arc-extinction ***,a theoretical method is proposed to reasonably address the discharge effects on C_(6)F_(12)O decomposition over typical Cu and Al electrodes at atomic *** results show that both the external electric field and the excess electrons could affect the activation of C_(6)F_(12)O by changing the electron acceptance of C_(6)F_(12)O and the orbital hybridisation during the surface *** metal surfaces,the C-F single bond in adsorbed C_(6)F_(12)O is the weakest position to decompose,and its cleavage could be promoted by the discharge *** the C-F breaking,the C-C cleavage remains unfavourable on Cu(111),but it is significantly promoted on Al(111),indicating a higher corrosion risk on the Al surface via continuous C_(6)F_(12)O *** proposed method as a valid supplement to the experiment reveals the discharge effects and the decomposition tendency of C_(6)F_(12)O on metal electrodes in discharge faults,which broadens the means for insulation gas evaluation.

关键词： corrosion insulation cleavage

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Assessing forest cover changes and fragmentation in the Himalayan temperate region: implications for forest conservation and management

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Journal of Forestry Research 2024年第4期35卷 128-141页

作者： Kaleem Mehmood Shoaib Ahmad Anees Akhtar Rehman Aqil Tariq Qijing Liu Sultan Muhammad Fazli Rabbi Shao’an Pan Wesam Atef Hatamleh College of Forestry Beijing Forestry UniversityBeijing 100083People’s Republic of China Institute of Agriculture Sciences and Forestry University of SwatSwatPakistan Department of Forestry The University of AgricultureDera Ismail Khan 29050Pakistan Key Laboratory for Silviculture and Conservation of Ministry of Education Beijing Forestry UniversityBeijing 100083People’s Republic of China Beijing Key Laboratory of Precision Forestry Forestry CollegeBeijing Forestry UniversityBeijing 100083People’s Republic of China School of Environmental Studies China University of GeosciencesWuhan 430074People’s Republic of China Department of Wildlife Fisheries and AquacultureCollege of Forest ResourcesMississippi State UniversityStarkvilleMS 39762‑9690USA School of Management Tianjin University of CommerceTianjin 300134People’s Republic of China Department of Computer Science College of Computer and Information SciencesKing Saud UniversityP.O.Box 5117811543 RiyadhSaudi Arabia

This study comprehensively assessed long-term vegetation changes and forest fragmentation dynamics in the Himalayan temperate region of Pakistan from 1989 to *** satellite images,including Landsat-5 TM and Landsat-8 Operational Land Imager(OLI),were chosen for subsequent assessments in October 1989,2001,2011 and *** classified maps of 1989,2001,2011 and 2019 were created using the maximum likelihood ***-classification comparison showed an overall accuracy of 82.5%and a Kappa coefficient of 0.79 for the 2019 *** revealed a drastic decrease in closed-canopy and open-canopy forests by 117.4 and 271.6 km^(2),respectively,and an increase in agriculture/farm cultivation by 1512.8 km^(2).The two-way ANOVA test showed statistically significant differences in the area of various cover *** fragmentation was evaluated using the Landscape Fragmentation Tool(LFT v2.0)between 1989 and *** large forest core(>2.00 km^(2))decreased from 149.4 to 296.7 km^(2),and a similar pattern was observed in medium forest core(1.00-2.00 km^(2))*** the contrary,the small core(<1.00 km^(2))forest increased from 124.8 to 145.3 km^(2) in *** perforation area increased by 296.9 km^(2),and the edge effect decreased from 458.9 to 431.7 km^(2).The frequency of patches also increased by 119.1 km^(2).The closed and open canopy classes showed a decreasing trend with an annual rate of 0.58%and 1.35%,*** broad implications of these findings can be seen in the studied region as well as other global ecological *** serve as an imperative baseline for afforestation and reforestation operations,highlighting the urgent need for efficient management,conservation,and restoration *** on these findings,sustainable land-use policies may be put into place that support local livelihoods,protect ecosystem services,and conserve biodiversity.

关键词： Natural catastrophes Landsat Change detection Forest fragmentation Landscape fragmentation tool(LFT) Afforestation Reforestation

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MADDPG-D2: An Intelligent Dynamic Task Allocation Algorithm Based on Multi-Agent Architecture Driven by Prior Knowledge

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2559-2586页

作者： Tengda Li Gang Wang Qiang Fu College of Air and Missile Defense Air Force Engineering UniversityXi’an710051China

Aiming at the problems of low solution accuracy and high decision pressure when facing large-scale dynamic task allocation(DTA)and high-dimensional decision space with single agent,this paper combines the deep reinforce-ment learning(DRL)theory and an improved Multi-Agent Deep Deterministic Policy Gradient(MADDPG-D2)algorithm with a dual experience replay pool and a dual noise based on multi-agent architecture is proposed to improve the efficiency of *** algorithm is based on the traditional Multi-Agent Deep Deterministic Policy Gradient(MADDPG)algorithm,and considers the introduction of a double noise mechanism to increase the action exploration space in the early stage of the algorithm,and the introduction of a double experience pool to improve the data utilization rate;at the same time,in order to accelerate the training speed and efficiency of the agents,and to solve the cold-start problem of the training,the a priori knowledge technology is applied to the training of the ***,the MADDPG-D2 algorithm is compared and analyzed based on the digital battlefield of ground and air *** experimental results show that the agents trained by the MADDPG-D2 algorithm have higher win rates and average rewards,can utilize the resources more reasonably,and better solve the problem of the traditional single agent algorithms facing the difficulty of solving the problem in the high-dimensional decision *** MADDPG-D2 algorithm based on multi-agent architecture proposed in this paper has certain superiority and rationality in DTA.

关键词： Deep reinforcement learning dynamic task allocation intelligent decision-making multi-agent system MADDPG-D2 algorithm

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Thermofluidic investigations of oil natural transformer:Closed-loop modelling and experimental validation

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High Voltage 2024年第1期9卷 230-240页

作者： Yuan Li Yiran Gao Chen Wang Chao Zhu Ying Li Yuankai Wang Guanjun Zhang State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina Electric Power Research Institute of State Grid Shaanxi Electric Power Co. Ltd.Xi'anChina TBEA Hengyang Transformer Co. Ltd.HengyangChina

Excessively high temperatures inside a power transformer can accelerate the ageing rate and even cause unplanned *** estimating the hot-spot temperature(HST)of a power transformer is important for regulating the load and ensuring long-term *** this study,a closed-loop model of a 110-kV product transformer with an oil natural/air forced(ONAF)cooling mode is built to predict HST,in which the compression ratio of windings,equivalent heat source and radiator geometry are *** to the flow field of the winding,the‘dead oil zone’and reverse oil flow are observed in the horizontal oil *** accuracy of the proposed model is experimentally validated by temperature-rise *** results show that the absolute errors between the measured results and simulation are below 5°C,and the average error is~2°***,the arrangements of windings and radiators are studied to enhance the oil *** adding 5 washers to the high-voltage winding,the average temperature can be decreased by 6°C compared with the case without a *** the radiator can also mitigate the characteristic temperatures,and the optimal height difference between the radiator and winding centre is suggested to be 0.66 m.

关键词： winding arrangement adding

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