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Application of GPR reverse time migration in tunnel lining cavity imaging 被引量:1
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作者 Lv Yu-zeng Wang Hong-hua Gong Jun-bo 《Applied Geophysics》 SCIE CSCD 2020年第2期277-284,316,共9页
Correctly locating the tunnel lining cavity is extremely important tunnel quality inspection.High-accuracy imaging results are hard to obtain because conventional one-way wave migration is greatly aff ected by lateral... Correctly locating the tunnel lining cavity is extremely important tunnel quality inspection.High-accuracy imaging results are hard to obtain because conventional one-way wave migration is greatly aff ected by lateral velocity change and inclination limitation and because the diff racted wave cannot be accurately returned to the real spatial position of the lining cavity.This paper presents a tunnel lining cavity imaging method based on the groundpenetrating radar(GPR)reverse-time migration(RTM)algorithm.The principle of GPR RTM is described in detail using the electromagnetic wave equation.The finite-difference timedomain method is employed to calculate the backward extrapolation electromagnetic fi elds,and the zero-time imaging condition based on the exploding-reflector concept is used to obtain the RTM results.On this basis,the GPR RTM program is compiled and applied to the simulated and observed GPR data of a typical tunnel lining cavity GPR model and a physical lining cavity model.Comparison of RTM and Kirchhoff migration results reveals that the RTM can better converge the diff racted waves of steel bar and cavity to their true position and have higher resolution and better suppress the eff ect of multiple interference and clutter scattering waves.In addition,comparison of RTM results of diff erent degrees of noise shows that RTM has strong anti-interference ability and can be used for the accurate interpretation of radar profi le in a strong interference environment. 展开更多
关键词 Tunnel lining cavity ground-penetrating radar(GPR) reverse-time migration(RTM) zero-time imaging condition
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THE INTERACTION OF PLANE SH-WAVES AND NON-CIRCULAR CAVITY SURFACED WITH LINING IN ANISOTROPIC MEDIA
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作者 史守峡 韩峰 +1 位作者 王振清 刘殿魁 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1996年第9期855-867,共13页
This is an expand of the complex function method in solving the problem of interaction of plane.SH-waves and non-circular cavity surfaced with linig in anisotropic media.the use the method similar to that incorporated... This is an expand of the complex function method in solving the problem of interaction of plane.SH-waves and non-circular cavity surfaced with linig in anisotropic media.the use the method similar to that incorporated in [2] added with Savin's method for solving stress concentration of non-circular cavity surfaced with lining in elasticity.Anisotropic media can be used ic simulate the conditions of thegeology.The solving proceeding for this problem can be processed conveniently in the manner similar to that introduced in [2].In this paper.as illustrated in example numerical studies have been done for a square cavity surfaced with lining in anisotropic media. 展开更多
关键词 SH-WAVES anisotropic media non-circular cavity surfaced with lining
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Er^(3+)-Yb^(3+) Co-Doped Fiber Ring and Line Laser
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作者 向望华 朱向宇 +1 位作者 裴新 张贵忠 《Transactions of Tianjin University》 EI CAS 2004年第2期102-104,共3页
Er3+-Yb3+ co-doped fiber of 2 m long is used as the laser gain medium. Two fiber lasers with different structures have been set up, one is the line cavity fiber laser with the dielectric mirror being replaced by an al... Er3+-Yb3+ co-doped fiber of 2 m long is used as the laser gain medium. Two fiber lasers with different structures have been set up, one is the line cavity fiber laser with the dielectric mirror being replaced by an all-fiber reflecting mirror,the other is the ring cavity all-fiber laser. Both set-ups have achieved lasing operation at the wavelength of 1.53 μm. Pumped by the 1 064 nm light from all-solid-state Nd ∶YAG laser, the two fiber lasers at 1 530 nm are operational. Their output powers are 7.8 mW and 2 mW with 130 mW and 160 mW pump powers. 展开更多
关键词 Er^(3+)-Yb^(3+) co-doped fiber laser line cavity ring cavity all-fiber reflecting mirror
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