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基于动态平面波的三维多尺度全波形反演方法 被引量:2
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作者 国运东 孟凡冰 +2 位作者 秦广胜 李传强 李庆洋 《石油物探》 CSCD 北大核心 2022年第4期616-624,共9页
全波形反演(FWI)是一种较为精确的速度建模方法,但是在缺少低频和背景速度场不准确的情况下,容易引起周波跳跃现象。为了快速构建三维背景速度模型,提出了一种新的平面波编码策略,即构建新的平面波形态——锥面波,通过控制射线参数,实... 全波形反演(FWI)是一种较为精确的速度建模方法,但是在缺少低频和背景速度场不准确的情况下,容易引起周波跳跃现象。为了快速构建三维背景速度模型,提出了一种新的平面波编码策略,即构建新的平面波形态——锥面波,通过控制射线参数,实现多尺度锥面波编码全波形反演方法(CFWI),达到反演背景速度模型的目的。通过动态锥面波编码策略,仅用少量的平面波,就可以实现背景速度场的建立,大大降低了反演的计算量。将动态锥面波反演方法应用于三维洼陷和逆冲速度模型测试,结合多震源的FWI(MFWI),对于较差的初始模型和不含低频地震数据,能够准确地反演出速度模型。 展开更多
关键词 全波形反演 平面波 多尺度 低波数 背景速度模型
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Sensitivity of the suspected blood indicator:An experimental study 被引量:1
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作者 Sung Chul Park Hoon Jai Chun +8 位作者 Eun Sun Kim Bora Keum Yeon Seok Seo Yong Sik Kim Yoon Tae Jeen Hong Sik Lee Soon Ho Um Chang Duck Kim Ho Sang Ryu 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第31期4169-4174,共6页
AIM: To investigate whether suspected blood indicator (SBI) in capsule endoscopy (CE) is affected by back- ground color and capsule passage velocity. METHODS: Experimental models of the small intestine construct... AIM: To investigate whether suspected blood indicator (SBI) in capsule endoscopy (CE) is affected by back- ground color and capsule passage velocity. METHODS: Experimental models of the small intestine constructed from paper in a variety of colors were used to simulate the background colors observed in CE im- ages. The background colors studied included very pale yellow, yellow, very pale magenta, light grayish pink, burnt sienna, and deep and dark brown, and red spots were attached inside them. An endoscopic capsule was manually passed through the models. The rate of detection of the red spots by the SBI was evaluated based on the colors of the models and the capsule pas- sage velocities (0.5 cm/s, 1 cm/s, and 2 cm/s).RESULTS: The rate of detection of the red spots byground color of the model (P 〈 0.001). Detection rates were highest for backgrounds of very pale magenta, burnt sienna, and yellow, in that order. They were lowest for backgrounds of dark brown and very pale yellow. The rate of detection of red spots by the SBI tended to decrease at rapid capsule passage velocities (1-2 cm/s) compared to slow velocities (0.5 cm/s) for backgrounds of very pale yellow (P = 0.042), yellow (P = 0.001), very pale magenta (P = 0.002), and burnt sien- na (P = 0.001). No significant differences in the rate of detection were observed according to velocity for light grayish pink (P = 0.643) or dark brown (P = 0.396). CONCLUSION: SBI sensitivity was affected by back- ground color and capsule passage velocity in the models. These findings may facilitate the rapid detection of bleeding lesions by CE. 展开更多
关键词 Capsule endoscopy Suspected blood indi-cator Sensitivity Background color Passage velocity
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