A 2.5-dimensional method in frequency wave-number domain is developed to investigate the mode waves in a deviated borehole penetrating a transversely isotropic formation. The phase velocity dispersion characteristics ...A 2.5-dimensional method in frequency wave-number domain is developed to investigate the mode waves in a deviated borehole penetrating a transversely isotropic formation. The phase velocity dispersion characteristics of the fast and slow flexural mode waves excited by a dipole source are computed accurately at various deviation angles for both hard and soft formations. The sensitivities of the flexural mode waves to all elastic constants in a transversely isotropic formation are calculated. Numerical results show that, for a soft formation, the fast flexural mode wave is dominated by c66 at high deviation angles and low frequencies, while the slow flexural mode wave is dominated by c44 at the same conditions. Waveforms in time domain are also presented to support the conclusions.展开更多
Electric field penetration is a consequence of solar wind interaction with planetary magnetosphere and/or ionosphere. For both Earth with intrinsic magnetosphere and Mars/Venus without intrinsic magnetosphere, the pen...Electric field penetration is a consequence of solar wind interaction with planetary magnetosphere and/or ionosphere. For both Earth with intrinsic magnetosphere and Mars/Venus without intrinsic magnetosphere, the penetration electric field causes various kinds of global and local electrodynamic response of the ionosphere to the solar wind electric field, especially the plasma motion in the ionosphere. Within the first 14 years of the twenty-first century, the cause and effect of the electric field penetra- tion on Earth has been investigated extensively and understood more deeply. Here we review the progress acquired on the patterns and drivers of the penetration electric field, and its influences on the plasma distribution and the equatorial spread F in the mid- and low-latitude ionosphere. From the perspective of comparative study, we also shortly introduce the new results for Mars. What has become clear is that our understanding of electric field penetration has been significantly improved, but ultimately the crucial details of the global picture still remain un- known. Looking forward to the future research of the electric field penetration in Earth＇s ionosphere, the break- through relies on new instruments built up at different longitudes to improve the global coverage of the observa- tion. An integrated network of instrument is necessary to reveal the longitude and local-time dependence of the electric field penetration and shed new light on the physical details of the global ionospheric processes driven by the electric field penetration.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11134011)the National R&D Projects for Key Scientific Instruments(Grant No.ZDYZ2012-1-07)the"12th Five-Year Plan"Period for Informatization Project in Supercomputing Key Demonstration,Chinese Academy of Sciences(Grant No.XXH12503-02-02-2(07))
文摘A 2.5-dimensional method in frequency wave-number domain is developed to investigate the mode waves in a deviated borehole penetrating a transversely isotropic formation. The phase velocity dispersion characteristics of the fast and slow flexural mode waves excited by a dipole source are computed accurately at various deviation angles for both hard and soft formations. The sensitivities of the flexural mode waves to all elastic constants in a transversely isotropic formation are calculated. Numerical results show that, for a soft formation, the fast flexural mode wave is dominated by c66 at high deviation angles and low frequencies, while the slow flexural mode wave is dominated by c44 at the same conditions. Waveforms in time domain are also presented to support the conclusions.
基金supported by the Thousand Young Talents Program of China,the National Basic Research Program of China(2011CB811405)the National Natural Science Foundation of China(41321003,41174136,41174138)
文摘Electric field penetration is a consequence of solar wind interaction with planetary magnetosphere and/or ionosphere. For both Earth with intrinsic magnetosphere and Mars/Venus without intrinsic magnetosphere, the penetration electric field causes various kinds of global and local electrodynamic response of the ionosphere to the solar wind electric field, especially the plasma motion in the ionosphere. Within the first 14 years of the twenty-first century, the cause and effect of the electric field penetra- tion on Earth has been investigated extensively and understood more deeply. Here we review the progress acquired on the patterns and drivers of the penetration electric field, and its influences on the plasma distribution and the equatorial spread F in the mid- and low-latitude ionosphere. From the perspective of comparative study, we also shortly introduce the new results for Mars. What has become clear is that our understanding of electric field penetration has been significantly improved, but ultimately the crucial details of the global picture still remain un- known. Looking forward to the future research of the electric field penetration in Earth＇s ionosphere, the break- through relies on new instruments built up at different longitudes to improve the global coverage of the observa- tion. An integrated network of instrument is necessary to reveal the longitude and local-time dependence of the electric field penetration and shed new light on the physical details of the global ionospheric processes driven by the electric field penetration.
