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基于拓展Volume-Time理论的串联空气间隙非同期击穿过程分析
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作者 姚晓飞 常晓雪 +5 位作者 丁健刚 陈佳莉 刘学 王建华 刘志远 耿英三 《高压电器》 北大核心 2025年第3期119-127,159,共10页
为了认识串联空气间隙的击穿过程,以球—球间隙为研究对象,设计了“非对称组合间隙”,即总间隙距离不变的条件下分别单独调整两个间隙的距离使上下间隙距离不一致。采用拓展Volume-Time理论计算了串联双间隙的U50%,并解释了雷电冲击电... 为了认识串联空气间隙的击穿过程,以球—球间隙为研究对象,设计了“非对称组合间隙”,即总间隙距离不变的条件下分别单独调整两个间隙的距离使上下间隙距离不一致。采用拓展Volume-Time理论计算了串联双间隙的U50%,并解释了雷电冲击电压下非对称组合空气间隙的非同期击穿物理过程。实验结果表明,上下间隙距离分布不均匀程度对串联空气间隙击穿电压和击穿延时的影响;不均匀程度较大时,较低电压下存在单个间隙放电、总体不击穿的现象,较高电压下两间隙将出现非同期击穿;不均匀程度较小时,两间隙同期击穿。为了解释这种现象,文中采用拓展Volume-Time理论,通过确定临界体积、临界面积等关键参数来计算串联双间隙的击穿电压。并把串联双空气间隙击穿的原因解释为,空气间隙电场的有效体积与有效面积超过临界值。因此,双间隙非同期击穿的产生是由于当一个间隙达到了击穿起始条件,而另一个间隙还未达到击穿起始条件。 展开更多
关键词 双断口开关 串联空气间隙 雷电冲击电压 非同期击穿特性 volume-time理论
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Preliminary Clinical Study of Real-time Three-dimensional Echo-cardiographic Volume-time Curve in Evaluating Left Ventricular Diastolic Function
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作者 费洪文 何亚乐 +3 位作者 侯跃双 许燕 黄新胜 冯碧霞 《Journal of Huazhong University of Science and Technology(Medical Sciences)》 SCIE CAS 2007年第4期475-478,共4页
The volume-time curve change in patients with normal left ventricular (LV) diastolic function and diastolic dysfunction was evaluated by real-time three-dimensional echocardiography (RT3DE). LV diastolic dysfuncti... The volume-time curve change in patients with normal left ventricular (LV) diastolic function and diastolic dysfunction was evaluated by real-time three-dimensional echocardiography (RT3DE). LV diastolic dysfunction was defined by E'〈A' in pulse-wave tissue Doppler for inter-ventricular septal (IVS) of mitral annulus. In 24 patients with LV diastolic dysfunction, including 12 patients with delayed relaxation (delayed relaxation group) and 12 patients with pseudo-normal function (pseudo-normal group) and 24 normal volunteers (control group), data of full-volume image were acquired by real-time three-dimensional echocardiography and subjected to volume-time curve analysis. EDV (end-diastolic volume), ESV (end-systolic volume), LVEF (left ventricular ejection fraction), PER (peak ejection rate), PFR (peak filling rate) from RT3DE were examined in the three groups. Compared to the control group, PFR (diastolic filling index of RT3DE) was significantly reduced in the delayed relaxation group and pseudo-normal group (P〈0.05). There were no significant differences in EDV, ESV, LVEE PER (P〉0.05). It is concluded that PFR, as a diastolic filling index of RT3DE, can reflect the early diastolic function and serve as a new non-invasive, quick and accurate tool for clinical assessment of LV diastolic function. 展开更多
关键词 real-time three-dimensional echocardiography left ventricular diastolic function volume-time curve
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