Air-gun arrays are used in marine-seismic exploration. Far-field wavelets in subsurface media represent the stacking of single air-gun ideal wavelets. We derived single air-gun ideal wavelets using near-field wavelets...Air-gun arrays are used in marine-seismic exploration. Far-field wavelets in subsurface media represent the stacking of single air-gun ideal wavelets. We derived single air-gun ideal wavelets using near-field wavelets recorded from near-field geophones and then synthesized them into far-field wavelets. This is critical for processing wavelets in marine- seismic exploration. For this purpose, several algorithms are currently used to decompose and synthesize wavelets in the time domain. If the traveltime of single air-gun wavelets is not an integral multiple of the sampling interval, the complex and error-prone resampling of the seismic signals using the time-domain method is necessary. Based on the relation between the frequency-domain phase and the time-domain time delay, we propose a method that first transforms the real near-field wavelet to the frequency domain via Fourier transforms; then, it decomposes it and composes the wavelet spectrum in the frequency domain, and then back transforms it to the time domain. Thus, the resampling problem is avoided and single air-gun wavelets and far-field wavelets can be reliably derived. The effect of ghost reflections is also considered, while decomposing the wavelet and removing the ghost reflections. Modeling and real data processing were used to demonstrate the feasibility of the proposed method.展开更多
This application note discusses the preliminary results of paleomagnetics studies of several incisions of the Paleozoic period the territory of Armenia and neighboring regions （Minor Caucasus）. It is supposed that b...This application note discusses the preliminary results of paleomagnetics studies of several incisions of the Paleozoic period the territory of Armenia and neighboring regions （Minor Caucasus）. It is supposed that before the Permian period the Armenian-lranian Mezocontinent was uniform with Afro-Arabia and only at the end of the late Paleozoic the formed Mesozoic ocean separated these areas from each other. A result of application of the complex laboratory investigations were identified from samples of primary magnetization the direction of which corresponds to the time of formation of the studied rocks. On the basis of paleomagnetic researches of Triassic, Permian, Devonian, Carbonian rocks a preliminary conclusion has been made about the dipole configuration of the geomagnetic field throughout Paleozoic. The comparison of the obtained data to paleomagnetic definitions of African, Arabian plates, Europe and the Siberian platform leads to the conclusion that the Minor Caucasus existed separately from the present general lithosphere blocks of Greater Caucasus and Europe.展开更多
The cases of cholera in Mariupol and adjacent areas which were observed within the period of May-August, 2011 are investigated. Thirty-two diseased and 22 vibriocarriers were found on the territory of the city in the ...The cases of cholera in Mariupol and adjacent areas which were observed within the period of May-August, 2011 are investigated. Thirty-two diseased and 22 vibriocarriers were found on the territory of the city in the course of epidemic. The potential sources of infection are specified. The ways to avoid similar situations in the future are suggested. The analysis of the locations of the cholera contamination sources results in the obvious conclusion that most of them are connected with the place where the river Kalmius meets the Azov Sea. Waste flow from the residential solid waste landfill brings a considerable harm to the river Kalmius and the Azov Sea.展开更多
The paper analyzes the variation characteristics of energy fields of seismicity 2.1≤M L ≤4.5 in Jiangsu and its neighboring areas during the period between January 1970 and December 2007.It also analyzes the variati...The paper analyzes the variation characteristics of energy fields of seismicity 2.1≤M L ≤4.5 in Jiangsu and its neighboring areas during the period between January 1970 and December 2007.It also analyzes the variations of time "weight" coefficients of the major typical energy fields,using random function theory with seismic energy fields as a space-time random function field based on Empirical Orthogonal Function (EOF) expansion methods.The results show that the expansion accuracy of the first seven typical fields is 0.9244.The strength of seismic energy varies remarkably in different tectonic blocks in the study area.High value areas are in middle and southern Jiangsu,and the south Yellow Sea.The distribution of the typical fields also shows that it is an area that affects most significantly the seismic energy fields of the study region.The time "weight" coefficients of the first six typical fields vary with time,and the amplitude of the variations has strong temporal correlations with moderate-strong earthquakes in the region.展开更多
结合2015年第1509号超强台风"灿鸿"期间在杭州九堡大桥的现场实测数据,基于WRF(weather research and forecasting)和LES(大涡模拟)的台风多尺度耦合数值模拟方法,重现了台风"灿鸿"的中小尺度发展演化过程,并对九...结合2015年第1509号超强台风"灿鸿"期间在杭州九堡大桥的现场实测数据,基于WRF(weather research and forecasting)和LES(大涡模拟)的台风多尺度耦合数值模拟方法,重现了台风"灿鸿"的中小尺度发展演化过程,并对九堡大桥周边台风风场进行多尺度精细化模拟;以多项式插值的方式解决疏网格向密网格的背景风场要素降尺度耦合问题;最后通过大涡模拟获得了九堡大桥周边地区30 min瞬态台风风场数据。模拟得到的瞬态风速结果与实测数据在统计意义上较为吻合,表明WRF-LES耦合系统能实现从气象中尺度到建筑小尺度的多尺度数值模拟,有效地获取一次台风过程中目标区域的瞬态台风风场。NSRFG(narrowband synthesis random flow generator)方法生成的入口脉动风速适用于局部台风风场的LES计算,模拟所得风速功率谱与实测结果在低频段基本一致。展开更多
基金supported by the Geosciences and Technology Academy of China University of Petroleum(East China)
文摘Air-gun arrays are used in marine-seismic exploration. Far-field wavelets in subsurface media represent the stacking of single air-gun ideal wavelets. We derived single air-gun ideal wavelets using near-field wavelets recorded from near-field geophones and then synthesized them into far-field wavelets. This is critical for processing wavelets in marine- seismic exploration. For this purpose, several algorithms are currently used to decompose and synthesize wavelets in the time domain. If the traveltime of single air-gun wavelets is not an integral multiple of the sampling interval, the complex and error-prone resampling of the seismic signals using the time-domain method is necessary. Based on the relation between the frequency-domain phase and the time-domain time delay, we propose a method that first transforms the real near-field wavelet to the frequency domain via Fourier transforms; then, it decomposes it and composes the wavelet spectrum in the frequency domain, and then back transforms it to the time domain. Thus, the resampling problem is avoided and single air-gun wavelets and far-field wavelets can be reliably derived. The effect of ghost reflections is also considered, while decomposing the wavelet and removing the ghost reflections. Modeling and real data processing were used to demonstrate the feasibility of the proposed method.
文摘This application note discusses the preliminary results of paleomagnetics studies of several incisions of the Paleozoic period the territory of Armenia and neighboring regions （Minor Caucasus）. It is supposed that before the Permian period the Armenian-lranian Mezocontinent was uniform with Afro-Arabia and only at the end of the late Paleozoic the formed Mesozoic ocean separated these areas from each other. A result of application of the complex laboratory investigations were identified from samples of primary magnetization the direction of which corresponds to the time of formation of the studied rocks. On the basis of paleomagnetic researches of Triassic, Permian, Devonian, Carbonian rocks a preliminary conclusion has been made about the dipole configuration of the geomagnetic field throughout Paleozoic. The comparison of the obtained data to paleomagnetic definitions of African, Arabian plates, Europe and the Siberian platform leads to the conclusion that the Minor Caucasus existed separately from the present general lithosphere blocks of Greater Caucasus and Europe.
文摘The cases of cholera in Mariupol and adjacent areas which were observed within the period of May-August, 2011 are investigated. Thirty-two diseased and 22 vibriocarriers were found on the territory of the city in the course of epidemic. The potential sources of infection are specified. The ways to avoid similar situations in the future are suggested. The analysis of the locations of the cholera contamination sources results in the obvious conclusion that most of them are connected with the place where the river Kalmius meets the Azov Sea. Waste flow from the residential solid waste landfill brings a considerable harm to the river Kalmius and the Azov Sea.
基金the Key Projects in the National S&T Pillar Program during the Eleventh "Five-year Plan" Period(2006BAC01B03-03-01),China Earthquake AdministrationYouth Fund of Earthquake Administration of Jiangsu Province(2009),China
文摘The paper analyzes the variation characteristics of energy fields of seismicity 2.1≤M L ≤4.5 in Jiangsu and its neighboring areas during the period between January 1970 and December 2007.It also analyzes the variations of time "weight" coefficients of the major typical energy fields,using random function theory with seismic energy fields as a space-time random function field based on Empirical Orthogonal Function (EOF) expansion methods.The results show that the expansion accuracy of the first seven typical fields is 0.9244.The strength of seismic energy varies remarkably in different tectonic blocks in the study area.High value areas are in middle and southern Jiangsu,and the south Yellow Sea.The distribution of the typical fields also shows that it is an area that affects most significantly the seismic energy fields of the study region.The time "weight" coefficients of the first six typical fields vary with time,and the amplitude of the variations has strong temporal correlations with moderate-strong earthquakes in the region.
文摘结合2015年第1509号超强台风"灿鸿"期间在杭州九堡大桥的现场实测数据,基于WRF(weather research and forecasting)和LES(大涡模拟)的台风多尺度耦合数值模拟方法,重现了台风"灿鸿"的中小尺度发展演化过程,并对九堡大桥周边台风风场进行多尺度精细化模拟;以多项式插值的方式解决疏网格向密网格的背景风场要素降尺度耦合问题;最后通过大涡模拟获得了九堡大桥周边地区30 min瞬态台风风场数据。模拟得到的瞬态风速结果与实测数据在统计意义上较为吻合,表明WRF-LES耦合系统能实现从气象中尺度到建筑小尺度的多尺度数值模拟,有效地获取一次台风过程中目标区域的瞬态台风风场。NSRFG(narrowband synthesis random flow generator)方法生成的入口脉动风速适用于局部台风风场的LES计算,模拟所得风速功率谱与实测结果在低频段基本一致。
