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直流GIS/GIL盆式绝缘子表面电荷主导积聚方式的转变机理 被引量:19
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作者 罗毅 唐炬 +2 位作者 潘成 林生军 王忠强 《电工技术学报》 EI CSCD 北大核心 2019年第23期5039-5048,共10页
构建气体侧传导(包含气体载流子产生、扩散、漂移、复合等输运过程)、绝缘材料体传导和表面传导共存条件下盆式绝缘子表面电荷积聚仿真模型,研究了三种参数变化条件下表面积聚特性。仿真表明,当气体中离子对生成率和绝缘子体电导率改变... 构建气体侧传导(包含气体载流子产生、扩散、漂移、复合等输运过程)、绝缘材料体传导和表面传导共存条件下盆式绝缘子表面电荷积聚仿真模型,研究了三种参数变化条件下表面积聚特性。仿真表明,当气体中离子对生成率和绝缘子体电导率改变时,绝缘子表面电荷极性会发生改变。在此过程中,表面电荷积聚主导途径会在气体侧传导和绝缘子体传导之间转变。根据净电荷值的规律分别定义离子对生成率和体电导率改变时积聚途径改变的临界值,由于电场分布的差异导致上表面及下表面的临界离子对生成率不同,临界体电导率为5.76×10-18S/m。当绝缘子表面电导率增大时,表面传导对电荷积聚的影响逐渐增大,可以推测出表面电导率足够大时,电荷积聚主导机理会转变为表面传导。该研究有助于理解表面电荷的积聚机理,并能够为抑制电荷积聚提供新的思路。 展开更多
关键词 直流GIS/GIL 表面电荷积聚 离子对生成率 表面电导率 体电导率
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SiC纤维表面C涂层的制备及介电性能研究 被引量:2
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作者 郑文景 周万城 +1 位作者 罗发 于新民 《材料工程》 EI CAS CSCD 北大核心 2009年第11期36-39,共4页
采用化学气相沉积(CVD)法,在SiC纤维表面沉积了100nm厚的C涂层,研究了制备温度对C涂层微观结构、单丝纤维体电导率及纤维编制体介电性能的影响。采用SEM和RAM显微技术(Raman microscopy)对C涂层的表面形貌和微观结构进行分析。结果表明... 采用化学气相沉积(CVD)法,在SiC纤维表面沉积了100nm厚的C涂层,研究了制备温度对C涂层微观结构、单丝纤维体电导率及纤维编制体介电性能的影响。采用SEM和RAM显微技术(Raman microscopy)对C涂层的表面形貌和微观结构进行分析。结果表明:保持C涂层厚度一致,当沉积温度由800℃升到900℃后,C涂层的石墨化程度提高,晶粒变大,SiC纤维单丝体电导率由0.745Ω-1.cm-1升到6.289Ω-1.cm-1;SiC纤维编制体的复介电常数实部由90升到132,介电损耗由0.95升到1.14,其中虚部由87升到150。实部增大与载流子浓度增大有关,虚部增大与材料漏导电有关。认为这是SiC纤维表面沉积的C层使纤维电导率增大所致。直流电导损耗是其主要损耗机制。 展开更多
关键词 化学气相沉积(CVD) SIC纤维 C涂层 体电导率 拉曼光谱 介电性能
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用改进的局域非线性迭代方法计算三维井间电磁场 被引量:4
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作者 魏宝君 张庚骥 胡波 《石油大学学报(自然科学版)》 CSCD 北大核心 2002年第3期124-127,共4页
提出了用改进的局域非线性迭代 (MLNI)计算体积分方程的方法 ,并计算了三维井间电磁场。将井间大尺度电导率异常体分为近场区域和远场区域两部分 ,它们的位置和尺寸均随场点位置的变化而改变。对近场区域影响的计算采用局域非线性近似 ... 提出了用改进的局域非线性迭代 (MLNI)计算体积分方程的方法 ,并计算了三维井间电磁场。将井间大尺度电导率异常体分为近场区域和远场区域两部分 ,它们的位置和尺寸均随场点位置的变化而改变。对近场区域影响的计算采用局域非线性近似 ;将远场区域的影响作为外部激励源 ,采用迭代方法进行计算。由于不必进行直接的大型矩阵求逆运算 ,因而与体积分方程的直接解法相比 ,所需的机时更少 ,并减少了对内存的要求。数值计算结果显示 ,该方法也适用于高电导率对比地层 ,且计算精度与体积分方程直接解法的精度相当 ,是一种计算井间大尺度异常体散射场的有效方法。 展开更多
关键词 局域非线性迭代法 积分方程 局域非线性近似 三维井间电磁场 电导率异常 数值计算
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Surface resistivity of carbonaceous fiber/PTFE antistatic coatings
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作者 张姗 王成国 +5 位作者 袁华 朱波 于美杰 张丙明 韩荣恒 李永威 《Journal of Central South University》 SCIE EI CAS 2014年第5期1689-1695,共7页
Abstract: PAN (Polyacrylonitrile)-based carbonaceous fibers were prepared at the heat treatment temperature (HTT) range of 650 to 900 ℃. The relationships among HTT, carbon content and volume resistivity of the ... Abstract: PAN (Polyacrylonitrile)-based carbonaceous fibers were prepared at the heat treatment temperature (HTT) range of 650 to 900 ℃. The relationships among HTT, carbon content and volume resistivity of the carbonaceous fibers were investigated. The carbonaceous fibers/PTFE (Polytetrafluoroethylene) antistatic coatings were prepared by the spraying technology and the effects of carbonaceous fibers and pigments on surface resistivity of the coatings were systematically discussed. Micrographs provide insight into the antistatic mechanism of the coating. The results show that carbon content of the carbonaceous fibers increases from 68.8% to 74.8% (mass fraction) and the volume resistivity decreases drastically from 1.94× 10^-3 to 8.27× 10 ^-2.cm. The surface resistivity of the antistatic coating is adjustable between 10^5 and 10^8Ω2 to fit the different antistatic materials. Static is dissipated by a conductive network of short fibers and the tunneling effect between the neighboring fibers and conductive pigments. Conductive pigments make the conductive network more perfect and improve the antistatic ability, but insulating pigments acting as barriers for the formation of conductive channel increases the surface resistivity of the coatings. The influence of pigments on the surface resistivity drops gradually with the decrease of the carbonaceous fibers volume resistivity. 展开更多
关键词 carbonaceous fiber antistatic coatings surface resistivity PIGMENT MECHANISM
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Thermal and solutal Marangoni convection in three-layered viscous flows:Insights for liquid metal battery optimization
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作者 SHAHEEN Sidra HUANG Hu-lin +2 位作者 ARAIN Muhammad Bilal BHATTI Muhammad Mubashir KHALIQUE Chaudry Masood 《Journal of Central South University》 2025年第6期2087-2100,共14页
This study examines the intricate occurrences of thermal and solutal Marangoni convection in three-layered flows of viscous fluids,with a particular emphasis on their relevance to renewable energy systems.This researc... This study examines the intricate occurrences of thermal and solutal Marangoni convection in three-layered flows of viscous fluids,with a particular emphasis on their relevance to renewable energy systems.This research examines the flow of a three-layered viscous fluid,considering the combined influence of heat and solutal buoyancy driven Rayleigh-Bénard convection,as well as thermal and solutal Marangoni convection.The homotopy perturbation method is used to examine and simulate complex fluid flow and transport phenomena,providing important understanding of the fundamental physics and assisting in the optimization of various battery configurations.The inquiry examines the primary elements that influence Marangoni convection and its impact on battery performance,providing insights on possible enhancements in energy storage devices.The findings indicate that the velocity profiles shown graphically exhibit a prominent core zone characterized by the maximum speed,which progressively decreases as it approaches the walls of the channel.This study enhances our comprehension of fluid dynamics and the transmission of heat and mass in intricate systems,which has substantial ramifications for the advancement of sustainable energy solutions. 展开更多
关键词 viscous fluid three-layered closed geometries electrical conductivity thermal convection solutal convection mass diffusivity homotopy perturbation methods
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