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介质中光脉冲的超光速问题分析
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作者 鲍倩倩 康大为 孟少英 《物理通报》 CAS 2023年第12期19-21,共3页
光具有相速度、群速度和波前速度,辨明三者与真空光速c之间的关系是十分必要的.光在折射率小于1的介质中传播时,相速度能够超光速;光脉冲在具有反常色散的介质中传播时,群速度能够超光速.在任何情况下,光脉冲的波前速度和信息传播速度... 光具有相速度、群速度和波前速度,辨明三者与真空光速c之间的关系是十分必要的.光在折射率小于1的介质中传播时,相速度能够超光速;光脉冲在具有反常色散的介质中传播时,群速度能够超光速.在任何情况下,光脉冲的波前速度和信息传播速度都无法超光速.通过在课程中引入光前驱波现象,说明光脉冲的波前速度无法超过真空光速c. 展开更多
关键词 速度 速度 波前速度 超光速
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Direct pre-stack depth migration on rugged topography
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作者 周竹生 陈高祥 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第9期2736-2742,共7页
Engineering seismic exploration aims at shallow imaging which is confused by statics if the surface is uneven. Direct pre-stack depth migration (DPDM) is based on accurate elevations of sources and receivers, by whi... Engineering seismic exploration aims at shallow imaging which is confused by statics if the surface is uneven. Direct pre-stack depth migration (DPDM) is based on accurate elevations of sources and receivers, by which static correction is completely abandoned before migration and surely the imaging quality is remarkably improved. To obtain some artificial shot gathers, high-order staggered-grid finite-difference (FD) method is adapted to model acoustic wave propagation. Since the shot gathers are always disturbed by regular interferences, the statics still must be applied to supporting the interference elimination by apparent velocity filtering method. Then all the shot gathers should be removed back to their original positions by reverse statics. Finally, they are migrated by pre-stack reverse-time depth migration and imaged. The numerical experiments show that the DPDM can ideally avoid the mistakes caused by statics and increase imaging precision. 展开更多
关键词 undulating topography seismic modeling static correction apparent velocity filtering direct pre-stack depth migration
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基于XGBoost算法的地震多数据体识别含油河道砂体 被引量:4
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作者 张艺山 徐怀宝 +3 位作者 齐洪岩 谢天寿 杨远峰 杨邦伟 《新疆石油地质》 CAS CSCD 北大核心 2020年第4期477-482,共6页
准噶尔盆地东部侏罗系多发育陆相河道砂体,砂体厚度小且横向连续性差,具有“一砂一藏”的特征,油水关系复杂,油气预测难度大,单一的地球物理信息难以准确确定河道砂体的分布特征和孔隙流体性质。为此,提出采用XGBoost算法从叠后地震剖... 准噶尔盆地东部侏罗系多发育陆相河道砂体,砂体厚度小且横向连续性差,具有“一砂一藏”的特征,油水关系复杂,油气预测难度大,单一的地球物理信息难以准确确定河道砂体的分布特征和孔隙流体性质。为此,提出采用XGBoost算法从叠后地震剖面、叠后纵波阻抗和叠前纵横波速度比3种地震数据体中提取含油河道砂体的特征,以有效描述这类河道砂体含油性的空间展布特征,降低了利用常规单一地震属性对含不同流体砂岩储集层预测的多解性。通过模型测试证明了该方法在识别陆相河道砂体的含油气性方面的可行性,并在实际应用中取得了较好的效果。 展开更多
关键词 准噶尔盆地 头屯河组 河道砂体 XGBoost算法 叠后纵阻抗 纵横速度 含油砂体预测 模型测试
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Prestack migration velocity analysis based on simplified two-parameter moveout equation 被引量:1
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作者 陈海峰 李向阳 +2 位作者 钱忠平 宋建军 赵桂玲 《Applied Geophysics》 SCIE CSCD 2016年第1期135-144,220,221,共12页
Stacking velocity V_(C2),vertical velocity ratio γ_0,effective velocity ratio γ_(eff),and anisotropic parameter x_(eff) are correlated in the PS-converted-wave(PS-wave) anisotropic prestack Kirchhoff time mi... Stacking velocity V_(C2),vertical velocity ratio γ_0,effective velocity ratio γ_(eff),and anisotropic parameter x_(eff) are correlated in the PS-converted-wave(PS-wave) anisotropic prestack Kirchhoff time migration(PKTM) velocity model and are thus difficult to independently determine.We extended the simplified two-parameter(stacking velocity V_(C2) and anisotropic parameter k_(eff)) moveout equation from stacking velocity analysis to PKTM velocity model updating and formed a new four-parameter(stacking velocity V_(C2),vertical velocity ratio γ_0,effective velocity ratio γ_(eff),and anisotropic parameter k_(eff)) PS-wave anisotropic PKTM velocity model updating and process flow based on the simplified twoparameter moveout equation.In the proposed method,first,the PS-wave two-parameter stacking velocity is analyzed to obtain the anisotropic PKTM initial velocity and anisotropic parameters;then,the velocity and anisotropic parameters are corrected by analyzing the residual moveout on common imaging point gathers after prestack time migration.The vertical velocity ratio γ_0 of the prestack time migration velocity model is obtained with an appropriate method utilizing the P- and PS-wave stacked sections after level calibration.The initial effective velocity ratio γ_(eff) is calculated using the Thomsen(1999) equation in combination with the P-wave velocity analysis;ultimately,the final velocity model of the effective velocity ratio γ_(eff) is obtained by percentage scanning migration.This method simplifies the PS-wave parameter estimation in high-quality imaging,reduces the uncertainty of multiparameter estimations,and obtains good imaging results in practice. 展开更多
关键词 PS-converted-wave PKTM velocity updating two-parameter moveout equation migration imaging
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Cellular Automaton Simulations for Target Waves in Excitable Media 被引量:1
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作者 张立升 邓敏艺 +2 位作者 孔令江 刘慕仁 唐国宁 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第1期171-174,共4页
Using the Greenberg-Hasting cellular automata model, we study the properties of target waves in excitable media under the no-flux boundary conditions. For the system has only one excited state, the computer simulation... Using the Greenberg-Hasting cellular automata model, we study the properties of target waves in excitable media under the no-flux boundary conditions. For the system has only one excited state, the computer simulation and analysis lead to the conclusions that, the number of refractory states does not influence the wave-front speed; the wave- front speed decreases as the excitation threshold increases and increases as the neighbor radius increases; the period of target waves is equal to the number of cell states; the excitation condition for target waves is that the wave-front speed must be bigger than half of the neighbor radius. 展开更多
关键词 cellular automata excitable media target wave
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