The long time practice of observational research on earthquake prediction has shown that the information on shortterm and imminent earthquake precursors can hardly be detected, but it is very important for practical ...The long time practice of observational research on earthquake prediction has shown that the information on shortterm and imminent earthquake precursors can hardly be detected, but it is very important for practical and effective earthquake prediction. The result of analysis and study in this paper has shown that the anomaly of quasi static atmospheric electric field may be a kind of reliable information on short term and imminent earthquake precursors.On such a basis, the 20 years′ continuous and reliable data of atmospheric electric field observed at the Baijiatuan seismic station are used to study the correlation between the anomalies in seismic activity and relative quiet periods bear on the occurrence of near earthquakes within 200 km range around Beijing after the Tangshan earthquake. The observational results recently reported before hand in written form and earthquakes that actually occurred in near field in corresponding time periods are compared and analyzed. The efficacy of these written prediction opinions about near earthquakes in the recent 10 years is tested. From the test results, the brilliant prospect that the anomaly of quasi static atmospheric electric field may really become a reliable mark for making short term and imminent earthquake predictions is discussed. Besides, as a preliminary step, some judgment indexes for predicting earthquakes by use of the observational data of atmospheric electric field before earthquakes are put forward. In the last part, it is pointed out that it would be possible to obtain more believable judgment indexes for determining the three elements of near earthquakes before greater earthquakes ( M S5) only if a relatively reasonable station network (2～4 stations every 10 000 km 2) is deployed and further investigation is made.展开更多
为了确定事故型撞击荷载作用下大型LNG储罐穹顶的局部破坏形态,以ф101.6 mm NPS法兰冲击能量为参照,选取穹顶局部壳体为靶体,利用等效飞射物弹体自由落体撞击靶体进行了15个工况冲击试验。通过对试验结果分析研究,标定了冲击成坑、冲...为了确定事故型撞击荷载作用下大型LNG储罐穹顶的局部破坏形态,以ф101.6 mm NPS法兰冲击能量为参照,选取穹顶局部壳体为靶体,利用等效飞射物弹体自由落体撞击靶体进行了15个工况冲击试验。通过对试验结果分析研究,标定了冲击成坑、冲击震裂、冲击剥落屈曲、冲击侵彻屈曲、冲击贯穿屈曲5种破坏形态,并给出了特征形态图。通过引入薄钢板弹道极限速度对侵彻贯穿屈曲破坏形态的侵彻深度进行修正,给出了以侵彻深度与穹顶厚度比值。这一无量纲参数为基准的破坏形态判断标准。最后,提出了事故型撞击荷载作用下LNG储罐穹顶的破坏等级划分标准,验证了Petry公式和BRL公式用于侵彻深度估算的有效性。展开更多
文摘The long time practice of observational research on earthquake prediction has shown that the information on shortterm and imminent earthquake precursors can hardly be detected, but it is very important for practical and effective earthquake prediction. The result of analysis and study in this paper has shown that the anomaly of quasi static atmospheric electric field may be a kind of reliable information on short term and imminent earthquake precursors.On such a basis, the 20 years′ continuous and reliable data of atmospheric electric field observed at the Baijiatuan seismic station are used to study the correlation between the anomalies in seismic activity and relative quiet periods bear on the occurrence of near earthquakes within 200 km range around Beijing after the Tangshan earthquake. The observational results recently reported before hand in written form and earthquakes that actually occurred in near field in corresponding time periods are compared and analyzed. The efficacy of these written prediction opinions about near earthquakes in the recent 10 years is tested. From the test results, the brilliant prospect that the anomaly of quasi static atmospheric electric field may really become a reliable mark for making short term and imminent earthquake predictions is discussed. Besides, as a preliminary step, some judgment indexes for predicting earthquakes by use of the observational data of atmospheric electric field before earthquakes are put forward. In the last part, it is pointed out that it would be possible to obtain more believable judgment indexes for determining the three elements of near earthquakes before greater earthquakes ( M S5) only if a relatively reasonable station network (2～4 stations every 10 000 km 2) is deployed and further investigation is made.
文摘为了确定事故型撞击荷载作用下大型LNG储罐穹顶的局部破坏形态,以ф101.6 mm NPS法兰冲击能量为参照,选取穹顶局部壳体为靶体,利用等效飞射物弹体自由落体撞击靶体进行了15个工况冲击试验。通过对试验结果分析研究,标定了冲击成坑、冲击震裂、冲击剥落屈曲、冲击侵彻屈曲、冲击贯穿屈曲5种破坏形态,并给出了特征形态图。通过引入薄钢板弹道极限速度对侵彻贯穿屈曲破坏形态的侵彻深度进行修正,给出了以侵彻深度与穹顶厚度比值。这一无量纲参数为基准的破坏形态判断标准。最后,提出了事故型撞击荷载作用下LNG储罐穹顶的破坏等级划分标准,验证了Petry公式和BRL公式用于侵彻深度估算的有效性。
