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基于硅橡胶分子链陷阱变化的复合绝缘子老化现象
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作者 沈瑶 刘兴杰 +2 位作者 梁英 薄天利 赵涛 《电工技术学报》 EI CSCD 北大核心 2024年第17期5545-5554,共10页
硅橡胶复合绝缘子老化后易引入乙烯基、羰基、羟基等强极性基团,形成化学性陷阱,进而加剧绝缘子老化甚至引发绝缘事故。为探究硅橡胶老化后不同化学基团的陷阱特性,以聚二甲基硅氧烷(PDMS)为基体,运用分子模拟软件分别构建含羰基、羟基... 硅橡胶复合绝缘子老化后易引入乙烯基、羰基、羟基等强极性基团,形成化学性陷阱,进而加剧绝缘子老化甚至引发绝缘事故。为探究硅橡胶老化后不同化学基团的陷阱特性,以聚二甲基硅氧烷(PDMS)为基体,运用分子模拟软件分别构建含羰基、羟基和乙烯基的PDMS缺陷模型,针对稳定构型后的缺陷模型,利用第一性原理,对含不同结构的PDMS在电场作用下的键长、键角、原子布局及偶极矩变化进行了计算,获得了对应的陷阱能级和态密度分布变化。通过分析不同缺陷模型的微观分子结构与陷阱特性之间的内在联系,探究了不同化学陷阱在电场作用下的变化规律。结果表明,含羟基的PDMS引入了浅陷阱,而含乙烯基和羰基的PDMS引入了深陷阱;三种缺陷的陷阱深度均随着电场的增大而增加,且变化率由大到小依次为羰基、乙烯基和羟基;随着电场的增大,含乙烯基的PDMS结构中出现了空穴陷阱,含羰基的PDMS中的电子陷阱出现了消散,而含羟基PDMS的陷阱分布变化不大。由此可见,硅橡胶老化后形成的羰基基团在其老化进程中的作用不容忽视。老化后的硅橡胶陷阱态和基团含量有望作为硅橡胶老化评估的新的参考标准,可为硅橡胶老化实验提供理论依据。 展开更多
关键词 硅橡胶 复合绝缘子 老化 化学陷阱 陷阱分布
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DPTM simulation of aeolian sand ripple 被引量:7
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作者 ZHENG XiaoJing bo tianli XIE Li 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2008年第3期328-336,共9页
Aeolian sand ripple and its time evolution are simulated by the discrete particle tracing method (DPTM) presented in this paper. The difference between this method and the current methods is that the former can consid... Aeolian sand ripple and its time evolution are simulated by the discrete particle tracing method (DPTM) presented in this paper. The difference between this method and the current methods is that the former can consider the three main factors relevant to the formation of natural aeolian sand ripples,which are the wind-blown sand flux above the sand bed formed by lots of sand particles with different di-ameters,the particle-bed collision and after it the rebound and ejection of sand particles in the sand bed,the saltation of high-speed sand particles and the creep of low-speed sand particles,respectively. The simulated aeolian sand ripple is close to the natural sand ripple not only in basic shape and characteristic,particle size segregation and stratigraphy,but also in formation stages. In addition,three important speeds can be obtained by this method,which are the propagation speed of the saturated aeolian sand ripple and the critical frictional wind speeds of emergence and disappearance of sand ripple. 展开更多
关键词 wind-blown SAND FLUX aeolian SAND RIPPLE DISCRETE particle TRACING method (DPTM) mixed-particle-size CREEP
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