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| 1 | Evaluation of Multi-Scale Full Waveform Inversion with Marine Vertical Cable Data显示文摘Seismic illumination plays an important role in subsurface imaging.A better image can be expected either through optimizing acquisition geometry or introducing more advanced seismic migration and/or tomographic inversion methods involving illumination compensation.Vertical cable survey is a potential replacement of traditional marine seismic survey for its flexibility and data quality.Conventional vertical cable data processing requires separation of primaries and multiples before migration.We proposed to use multi-scale full waveform inversion(FWI) to improve illumination coverage of vertical cable survey.A deep water velocity model is built to test the capability of multi-scale FWI in detecting low velocity anomalies below seabed.Synthetic results show that multi-scale FWI is an effective model building tool in deep-water exploration.Geometry optimization through target oriented illumination analysis and multi-scale FWI may help to mitigate the risks of vertical cable survey.The combination of multi-scale FWI,low-frequency data and multi-vertical-cable acquisition system may provide both high resolution and high fidelity subsurface models. | Aifei Bian Zhihui Zou Hua-Wei Zhou Jin Zhang | 2015 | Journal of Earth Science2015，26，4： | 4 |
| 2 | Impact and Solutions of Seawater Heterogeneity on Wide-Angle Tomographic Inversion of Crustal Velocities in Deep Marine Environments—Numerical Studies显示文摘The seawater column is typically taken as a homogeneous velocity layer in wide-angle crustal seismic surveys in marine environments. However, heterogeneities in salinity and temperature throughout the seawater layer result insignificant lateral variations in its seismic velocity, especially in deep marine environments. Failure to compensate for these velocity inhomogeneities will introduce significant artifacts in constructing crustal velocity models using seismic tomography. In this study, we conduct numerical experiments to investigate the impact of heterogeneous seismic velocities in seawater on tomographic inversion for crustal velocity models. Experiments that include lateral variation in seawater velocity demonstrated that the modeled crustal velocities were contaminated by artifacts from tomographic inversions when assuming a homogeneous water layer. To suppress such artifacts, we propose two strategies:(1) simultaneous inversion of water velocities and the crustal velocities;(2) layer-stripping inversion during which to first invert for seawater velocity and then correct the travel times before inverting for crustal velocities. The layer-stripping inversion significantly improves the modeling of variation in seawater velocity when preformed with seismic sensors deployed on the ocean bottom and in the water column. Such strategies improve crustal modeling via wide-angle seismic surveys in deep-marine environment. | Zhihui Zou Hua-Wei Zhou Harold Gurrola Aifei Bian Zhonglai Huang Jianzhong Zhang | 2018 | Journal of Earth Science2018，29，6： | 3 |
| 3 | Enhanced U(Ⅵ) bioreduction by alginate-immobilized uranium-reducing bacteria in the presence of carbon nanotubes and anthraquinone-2,6-disulfonate显示文摘Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2,6-disulfonate(AQDS), and carbon nanotubes(CNTs). The effects of different AQDS-CNTs contents, U(Ⅳ) concentrations, and metal ions on U(Ⅳ) reduction by immobilized beads were examined. Over 97.5% U(Ⅵ)(20 mg/L) was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U(Ⅵ) occurred at initial U(Ⅵ) concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe(Ⅲ), Cu(Ⅱ) and Mn(Ⅱ)slightly increased U(Ⅵ) reduction, whereas Cr(Ⅵ), Ni(Ⅱ), Pb(Ⅱ), and Zn(Ⅱ) significantly inhibited U(Ⅵ) reduction. After eight successive incubation-washing cycles or 8 hr of retention time(HRT) for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters. | Weida Wang Yali Feng Xinhua Tang Haoran Li Zhuwei Du Aifei Yi Xu Zhang | 2015 | Journal of Environmental Sciences2015，27，5： | 3 |
| 4 | An Evaluation of Reverse-Time Imaging of Clustering Earthquakes显示文摘Clustering earthquakes refer to the seismic events that occur closely with each other in time and space.Because their overlapping waveform records make it difficult to pick the first arrivals,the hypocenters of clustering earthquakes cannot be determined accurately by traveltime location methods.Here we apply a reverse-time imaging(RTI) method to map clustering earthquakes.Taking the advantage of directly using waveforms,the RTI method is capable to map either a single small earthquake or some densely distributed clustering earthquakes beneath a 2-D seismic array.In 3-D case the RTI method is successfully applied to locate the long-offset doublet earthquakes using the data from a set of sparsely distributed surface stations.However,for the same acquisition geometry,the RTI encounters challenges in mapping densely distributed clustering earthquakes.While it is obvious that improving the mapping of clustering earthquakes requires a denser receiver network with wider range of illumination angles,it is necessary to verify the actual resolution of the RTI method with synthetic data.In our study area in the Three Gorges region,our tests in 3-D case suggest that some events beneath the linear aligned sub-arrays have reasonable resolution. | Zhihui Zou Hua-Wei Zhou Aifei Bian Jianzhong Zhang Lei Xing | 2015 | Journal of Earth Science2015，26，4： | 2 |
| 5 | Large-scale synthesis of isolated Mn2O_(3) nanotube/fiber with ferric nitrate as catalyst显示文摘Isolated Mn2O_(3) nanotubes and nanofibers were prepared very easily at a large scale with the liquid-phase catalysis method.The Mn2O_(3) nanotubes had dimensions of 30–50 nm(exterior diameter)and 0.2–1.0 mm(length),approximately.The Mn2O_(3) nanofibers had dimensions of 10–30 nm(diameter)and 0.4–2.0 mm(length),approxim-ately.Nano-Mn2O_(3) with different microstructures including nanotubes,nanofibers and nanoparticles could be selectively synthesized by controlling the contents and proportions of potassium permanganate and ferric nitrate.Ferric nitrate was an ideal catalyst for the preparation of Mn2O_(3) nanotube/fiber.When cobalt nitrate or nickel nitrate was used as catalyst,only amorphous nano-Mn2O_(3) was synthesized.X-ray diffraction(XRD)result shows that the Mn2O_(3) nanotube has a crystalline structure different from o-Mn2O_(3),t-Mn2O_(3),h-Mn2O_(3) and c-Mn2O_(3). | ZHANG Aifei LIU Jiping LÜ Guangshu | 2007 | Frontiers of Chemical Science and Engineering2007，1，1： | 0 |
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