Earthquake magnitude and rupture duration are among the most important parameters characterizing an earthquake for the purpose of early tsunami warning. While they can be routinely determined from broadband P waveform...Earthquake magnitude and rupture duration are among the most important parameters characterizing an earthquake for the purpose of early tsunami warning. While they can be routinely determined from broadband P waveforms with iterative inver- sion procedures, the inversion procedures may fail when the rupture either lasts longer than the interval between P and later ar- rivals or requires too much time or human intervention. Little contaminated by later arrivals, high frequency P waves are useful for modeling earthquake source processes, though the envelope waveform is affected by strong scattering in lithosphere. With high frequency envelopes from aftershocks as Empirical Green＇s Function （EGF）, the coda effects can be removed and more accurate relative source time function （RSTF） of the main shock can be obtained. Assuming that RSTFs cannot be negative, we use the projected Landweber deconvolution method （PLD） to obtain high frequency RSTFs because PLD method has the ad- vantage of non-negativity, causality, and compactness （finite duration）. We are able to determine rupture durations of four large earthquakes： the 2004 Sumatra-Andaman earthquake, the 2005 Nias event, the 2006 Java event, and the 2011 Tokuko earthquake. The rupture durations of the Sumatra-Andaman, Nias, and Tohuko events are found to be around 550, 1 i0, and 120 s respectively, consistent with previous studies. The rupture duration of the Java event is about 130 s, supporting that the Java event is a tsunami earthquake. The magnitudes of these earthquakes are found to depend on both the amplitude and the duration of the deconvolved waveforms, and can be approximated by integrating these waveforms.展开更多
为了提高天然气燃烧速度,促进火焰传播,提高火焰稳定性,研究了稀燃条件下电场对层流预混火焰的影响。进行了常温、常压下的定容燃烧弹试验,分析了负电场和高频交流电场对天然气/空气预混稀燃火焰形状、燃烧压力、压力升高率、火焰燃烧...为了提高天然气燃烧速度,促进火焰传播,提高火焰稳定性,研究了稀燃条件下电场对层流预混火焰的影响。进行了常温、常压下的定容燃烧弹试验,分析了负电场和高频交流电场对天然气/空气预混稀燃火焰形状、燃烧压力、压力升高率、火焰燃烧期的影响。结果表明:过量空气系数1.6下,加载交直流电场均使火焰发生形变;当加载直流-5 kV电场与有效值为5 kV频率5、10、15和25 k Hz交流电场时,燃烧压力峰值分别增大6.96%、8.84%、10.50%、13.78%、14.40%,峰值到达时间提前14.67%、13.58%、18.93%、25.41%、27.97%;加载交直流电场,主要使火焰初始燃烧期缩短。交直流电场对火焰均有促进作用,且高频交流电场对火焰的促进作用优于直流电场。展开更多
基金supported by Chinese Academy of Sciences (Grant No. KZCX2-YE-142)National Natural Science Foundation of China(Grant Nos. 40974034, 41174086, 41021003)Chinese Academy of Sciences (Grant No. KZCX2-YW-116)
文摘Earthquake magnitude and rupture duration are among the most important parameters characterizing an earthquake for the purpose of early tsunami warning. While they can be routinely determined from broadband P waveforms with iterative inver- sion procedures, the inversion procedures may fail when the rupture either lasts longer than the interval between P and later ar- rivals or requires too much time or human intervention. Little contaminated by later arrivals, high frequency P waves are useful for modeling earthquake source processes, though the envelope waveform is affected by strong scattering in lithosphere. With high frequency envelopes from aftershocks as Empirical Green＇s Function （EGF）, the coda effects can be removed and more accurate relative source time function （RSTF） of the main shock can be obtained. Assuming that RSTFs cannot be negative, we use the projected Landweber deconvolution method （PLD） to obtain high frequency RSTFs because PLD method has the ad- vantage of non-negativity, causality, and compactness （finite duration）. We are able to determine rupture durations of four large earthquakes： the 2004 Sumatra-Andaman earthquake, the 2005 Nias event, the 2006 Java event, and the 2011 Tokuko earthquake. The rupture durations of the Sumatra-Andaman, Nias, and Tohuko events are found to be around 550, 1 i0, and 120 s respectively, consistent with previous studies. The rupture duration of the Java event is about 130 s, supporting that the Java event is a tsunami earthquake. The magnitudes of these earthquakes are found to depend on both the amplitude and the duration of the deconvolved waveforms, and can be approximated by integrating these waveforms.
文摘为了提高天然气燃烧速度,促进火焰传播,提高火焰稳定性,研究了稀燃条件下电场对层流预混火焰的影响。进行了常温、常压下的定容燃烧弹试验,分析了负电场和高频交流电场对天然气/空气预混稀燃火焰形状、燃烧压力、压力升高率、火焰燃烧期的影响。结果表明:过量空气系数1.6下,加载交直流电场均使火焰发生形变;当加载直流-5 kV电场与有效值为5 kV频率5、10、15和25 k Hz交流电场时,燃烧压力峰值分别增大6.96%、8.84%、10.50%、13.78%、14.40%,峰值到达时间提前14.67%、13.58%、18.93%、25.41%、27.97%;加载交直流电场,主要使火焰初始燃烧期缩短。交直流电场对火焰均有促进作用,且高频交流电场对火焰的促进作用优于直流电场。
