A kinetic model of dielectric ageing is presented. The central finding of this investigation is that there is a power-law relationship between the local electric field concentration and the rate of defect-tip initiate...A kinetic model of dielectric ageing is presented. The central finding of this investigation is that there is a power-law relationship between the local electric field concentration and the rate of defect-tip initiated conducting crack growth. By applying such a power-law conducting crack growth rate expression to the evaluation of the life of solid dielectrics, the empirical classical ageing law of insulation materials can be derived theoretically as a lobical result. All the results are universal and agree with the experimental data of oxide films.展开更多
为研究材料类型和参数对绝缘子电场强度和电位分布的影响,采用有限元法以支柱绝缘子为对象研究了柱体和伞裙材料分别为电瓷、玻璃、高温硫化(high temperature vulcanization,HTV)硅橡胶时绝缘子及附近场强、电位分布以及沿面和干弧路...为研究材料类型和参数对绝缘子电场强度和电位分布的影响,采用有限元法以支柱绝缘子为对象研究了柱体和伞裙材料分别为电瓷、玻璃、高温硫化(high temperature vulcanization,HTV)硅橡胶时绝缘子及附近场强、电位分布以及沿面和干弧路径上场强和电位,同时研究了材料的电阻率和相对介电常数对绝缘子附近场强和电位分布的影响。结果表明:支柱绝缘子场强度、电位分布极不均匀,上金具附近场强大、电位集中,从上到下沿面场强、电位下降速度有下降趋势,材料类型基本不影响整体场强和电位以及等位线;从最大场强和电位集中程度来看HTV>电瓷>玻璃;伞裙存在会畸变其附近场强,伞裙上表面与柱体交汇处、伞裙下表面各棱底部附近场强畸变相对严重。正常范围内绝缘材料的体积电阻率对场强和电位分布未见影响;随着相对介电常数的增加最大场强减少,沿面和干弧路径上电位分布更均匀,但伞裙附近场强畸变加剧。展开更多
In order to solve for temperature fields in microwave heating for recycling asphalt mixtures, a two-dimensional heat transfer model for the asphalt mixtures within the heating range is built based on the theory of uns...In order to solve for temperature fields in microwave heating for recycling asphalt mixtures, a two-dimensional heat transfer model for the asphalt mixtures within the heating range is built based on the theory of unsteady heat conduction. Four onedimensional heat transfer models are established for the asphalt mixtures outside the heating range, which are simplified into four half-infinite solids. The intensity of the radiation electric field is calculated through experiment by using heating water loads. It is suggested that the mathematical model of boundary conditions can be established in two ways, which are theoretical deduction and experimental reverse. The actual temperature field is achieved by fitting temperatures of different positions collected in the heating experiment. The simulant temperature field, which is solved with the Matlab PDE toolbox, is in good agreement with the actual temperature field. The results indicate that the proposed models have high precision and can be directly used to calculate the temperature distribution of asphalt pavements.展开更多
为了研究同轴线筒电极在大气压下空气中的电气参数和放电机理,利用有限元软件Comsol的等离子体模块,建立了大气压空气中一维线筒电极放电的等离子体模型,并对放电过程进行求解,得到放电过程中气隙的电场强度及电子密度随时间变化的图形...为了研究同轴线筒电极在大气压下空气中的电气参数和放电机理,利用有限元软件Comsol的等离子体模块,建立了大气压空气中一维线筒电极放电的等离子体模型,并对放电过程进行求解,得到放电过程中气隙的电场强度及电子密度随时间变化的图形,放电过程中电子密度高达1014m-3,此时对应的放电电流为毫安级。在大气压空气中对线筒电极也进行了放电实验,在不同的外加电压下,测出线筒电极的放电电流分别约为1 m A和5 m A,仿真结果与实验数据相吻合。展开更多
文摘A kinetic model of dielectric ageing is presented. The central finding of this investigation is that there is a power-law relationship between the local electric field concentration and the rate of defect-tip initiated conducting crack growth. By applying such a power-law conducting crack growth rate expression to the evaluation of the life of solid dielectrics, the empirical classical ageing law of insulation materials can be derived theoretically as a lobical result. All the results are universal and agree with the experimental data of oxide films.
文摘为研究材料类型和参数对绝缘子电场强度和电位分布的影响,采用有限元法以支柱绝缘子为对象研究了柱体和伞裙材料分别为电瓷、玻璃、高温硫化(high temperature vulcanization,HTV)硅橡胶时绝缘子及附近场强、电位分布以及沿面和干弧路径上场强和电位,同时研究了材料的电阻率和相对介电常数对绝缘子附近场强和电位分布的影响。结果表明:支柱绝缘子场强度、电位分布极不均匀,上金具附近场强大、电位集中,从上到下沿面场强、电位下降速度有下降趋势,材料类型基本不影响整体场强和电位以及等位线;从最大场强和电位集中程度来看HTV>电瓷>玻璃;伞裙存在会畸变其附近场强,伞裙上表面与柱体交汇处、伞裙下表面各棱底部附近场强畸变相对严重。正常范围内绝缘材料的体积电阻率对场强和电位分布未见影响;随着相对介电常数的增加最大场强减少,沿面和干弧路径上电位分布更均匀,但伞裙附近场强畸变加剧。
基金The Key Project of Science and Technology of Ministryof Education (No.105085)the Specialized Research Fund of Science andTechnology Production Translation of Jiangsu Province (No.BA2006068).
文摘In order to solve for temperature fields in microwave heating for recycling asphalt mixtures, a two-dimensional heat transfer model for the asphalt mixtures within the heating range is built based on the theory of unsteady heat conduction. Four onedimensional heat transfer models are established for the asphalt mixtures outside the heating range, which are simplified into four half-infinite solids. The intensity of the radiation electric field is calculated through experiment by using heating water loads. It is suggested that the mathematical model of boundary conditions can be established in two ways, which are theoretical deduction and experimental reverse. The actual temperature field is achieved by fitting temperatures of different positions collected in the heating experiment. The simulant temperature field, which is solved with the Matlab PDE toolbox, is in good agreement with the actual temperature field. The results indicate that the proposed models have high precision and can be directly used to calculate the temperature distribution of asphalt pavements.
文摘为了研究同轴线筒电极在大气压下空气中的电气参数和放电机理,利用有限元软件Comsol的等离子体模块,建立了大气压空气中一维线筒电极放电的等离子体模型,并对放电过程进行求解,得到放电过程中气隙的电场强度及电子密度随时间变化的图形,放电过程中电子密度高达1014m-3,此时对应的放电电流为毫安级。在大气压空气中对线筒电极也进行了放电实验,在不同的外加电压下,测出线筒电极的放电电流分别约为1 m A和5 m A,仿真结果与实验数据相吻合。
