Target-oriented Q-compensated reverse-time migration by using optimized pure-mode wave equation in anisotropic media

Research on seismic anisotropy and attenuation plays a significant role in exploration geophysics. To enhance the imaging quality for complicated structures, we develop several effective improvements for anisotropic attenuation effects in reverse-time migration (Q-RTM) on surface and vertical seismic profiling (VSP) acquisition geometries. First, to suppress pseudo-shear wave artifact and numerical instability of the commonly used anisotropic pseudo-acoustic wave equations, an optimized pure P-wave dispersion relation is derived and the corresponding pure-mode wave equation is solved by combining the finite-difference and Possion methods. Second, a simplified anisotropic pure-mode visco-acoustic wave equation (PVAWE) based on standard linear solid model is established. Third, a time-dispersion correlation strategy is applied to improve the modeling accuracy. Fourth, we extend a target-oriented scheme to anisotropic attenuated modeling and imaging. Instead of the conventional wavefield modeling and RTM, the proposed approach can extract available wavefield information near the target regions and produce high imaging resolution for target structures. Last, both anisotropic surface and VSP Q-RTMs are executed by combining optimized PVAWE, time-dispersion correlation and target-oriented algorithm. Modeling examples demonstrate the advantages of our schemes. Moreover, our modified Q-compensated imaging workflow can be regarded as a supplement to the classical anisotropic RTM.

Target-oriented Gaussian beam migration using a modif ied ray tracing scheme

For large-scale 3D seismic data,target-oriented reservoir imaging is more attractive than conventional full-volume migration,in terms of computation efficiency.Gaussian beam migration(GBM)is one of the most robust depth imaging method,which not only keeps the advantages of ray methods,such as high efficiency and flexibility,but also allows us to solve caustics and multipathing problems.But conventional Gaussian beam migration requires slant stack for prestack data,and ray tracing from beam center location to subsurface,which is not easy to be directly applied for target-oriented imaging.In this paper,we modify the conventional Gaussian beam migration scheme,by shooting rays from subsurface image points to receivers to implement wavefield back-propagation.This modification helps us to achieve a better subsurface illumination in complex structure and allows simple implementation for target reservoir imaging.Significantly,compared with the wavefi eld-based GBM,our method does not reconstruct the subsurface snapshots,which has higher efficiency.But the proposed method is not as efficient as the conventional Gaussian beam migration.Synthetic and field data examples demonstrate the validity and the target-oriented imaging capability of our method.

TARGET-ORIENTED POVERTY ALLEVIATION TAKING PLACE ON THE PLATEAU

Tibet,the only provincial-level impoverished region,is facing great challenges in getting rid of poverty,such as widespread poverty and weak infrastructure.Since 2012,Tibet has launched its "five in one" project and has gradually formed a layout for a large poverty-

Wolfberry tree dual-model detection method and orchard target-oriented fertilization system based on photoelectric sensors

Orchard target-oriented fertilizing with on-board sensor technology can improve fertilizer efficiency and reduce environmental pollution.Photoelectric sensors are widely used for object detection because of their low cost and fast response time.This paper presents a Wolfberry tree dual-model detection method and the design of an orchard target-oriented variable-rate fertilization system based on photoelectric sensors.The dual-model detection method includes the Trunk Detection Model(TDM)and Canopy Detection Model(CDM),which can be applied for Wolfberry orchards at the green cluster and mature stages,respectively.A target-oriented fertilization system was designed using the dual-model method,and tested in the lab and Chinese Wolfberry orchard.The laboratory test results showed that the average center offset distances on the condition of detecting trunks,continuous canopies,and discontinuous canopies were 4.1 cm,9.1 cm and 13.1 cm,respectively.The system could ignore the signals from canes when their diameters were less than 16 mm,and also could determine the gaps within a tree when they were less than 21 cm.The orchard test results showed that the system accomplished target-oriented fertilization 95 times for 92 trees at the mature stage.The results indicated that the dual-model detection method could be used for Wolfberry trees or other trees with similar canopy changes at different growth stages.

AN EFFICIENT AND TARGET-ORIENTED SAMPLE ENRICHMENT METHOD FOR PREPARATIVE SEPARATION OF MINOR ALKALOIDS BY PH-ZONE-REFINING COUNTER-CURRENT CHROMATOGRAPHY

A sample enrichment method focusing on the minor targeted components was established to help them to be successfully separated by pH-zone refining CCC.Seven minor indole alkaloids in Uncaria rhynchophylla(Miq.)Miq.ex Havil(UR)were chosen to show the advantage of this method.The sample enrichment and separation were

Target-oriented Passive Localization Techniques Inspired by Terrestrial Arthropods: A Review

For centuries,researchers have been fascinated by how simple-minded arthropods pick up definite cues and locate a potential target in an instant.Contrary to the active echolocation of classical creatures,arthropods exhibit passive characteristics.They use spatially separated sensilla to cooperatively pinpoint target-generated signal sources such as sound,light,ground vibration,air disturbance,and thermal radiation.The paper introduces the localization mechanisms of typical terrestrial arthropods with diverse survival habits.Focusing on these special mechanisms,a series of theoretical models and advanced bionic equipment have been reviewed,and some key challenges and future directions are proposed.We believe that intensive study on arthropods can promote innovative development of miniaturized,low power-dissipation,and high-performance localization equipment,thereby enhancing and expanding current localization techniques.

Target-oriented robust optimization of a microgrid system investment model

An emerging alternative solution to address energy shortage is the construction of a microgrid system. This paper develops a mixed-integer linear programming microgrid investment model considering multi-period and multi-objective investment setups. It further investigates the effects of uncertain demand by using a target-oriented robust optimization （TORO） approach. The model was validated and analyzed by subjecting it in different scenarios. As a result, it is seen that there are four factors that affect the decision of the model： cost, budget, carbon emissions, and useful life. Since the objective of the model is to maximize the net present value （NPV） of the system, the model would choose to prioritize the least cost among the different distribution energy resources （DER）. The effects of load uncertainty was observed through the use of Monte Carlo simulation. As a result, the deterministic model shows a solution that might be too optimistic and might not be achievable in real life situations. Through the application of TORO, a profile of solutions is generated to serve as a guide to the investors in their decisions considering uncertain demand. The results show that pessimistic investors would have lower NPV targets since they would invest more in storage facilities, incurring more electricity stock out costs. On the contrary, an optimistic investor would tend to be aggressive in buying electricity generating equipment to meet most of the demand, however risking more storage stock out costs.

Target-Oriented Inversion of Time-Lapse Seismic Waveform Data

Full waveform inversion of time-lapse seismic data can be used as a means of estimating the reservoir changes due to the production.Since the repeated computa-tions for the monitor surveys lead to a large computational cost,time-lapse full wave-form inversion is still considered to be a challenging task.To address this problem,we present an efficient target-oriented inversion scheme for time-lapse seismic data using an integral equation formulation with Gaussian beam based Green’s function approach.The proposed time-lapse approach allows one to perform a local inversion within a small region of interest(e.g.a reservoir under production)for the monitor survey.We have verified that the T-matrix approach is indeed naturally target-oriented,which was mentioned by Jakobsen and Ursin[24]and allows one to reduce the compu-tational cost of time-lapse inversion by focusing the inversion on the target-area only.This method is based on a new version of the distorted Born iterative T-matrix inverse scattering method.The Gaussian beam and T-matrix are used in this approach to perform the wavefield computation for the time-lapse inversion in the baseline model from the survey surface to the target region.We have provided target-oriented inversion results of the synthetic time-lapse waveform data,which shows that the proposed scheme reduces the computational cost significantly.

的语视角下翻译的不对等问题研究

实际翻译中经常出现原文和译文在各方面的不对等现象。本文首先回顾翻译研究领域对“对等”的研究成果 ,再把关注焦点放到作为例外的“不对等”现象上 ,在进一步分析不对等现象出现的原因和适宜程度等问题时 ,本文借助文化操纵理论观 ,指出的语的文化底蕴和价值等是重要的影响因素 。

正确把握就业导向内涵,全面实现中等职业教育培养目标

当前以就业为导向在中等职业教育的实践过程中并没有真正的落实。中等职业教育应全面理解以就业为导向的内涵,认真执行中等职业教育的教学计划,切实保证文化课及专业基础课教学质量,提高学生的综合素质和就业能力,积极开展创业教育,注重学生创业能力和创新精神的培养,全面实现中等职业教育的培养目标。

Transition Operator Approach to Seismic Full-Waveform Inversion in Arbitrary Anisotropic Elastic Media

We generalize the existing distorted Born iterative T-matrix(DBIT)method to seismic full-waveform inversion(FWI)based on the scalar wave equation,so that it can be used for seismic FWI in arbitrary anisotropic elastic media with variable mass densities and elastic stiffness tensors.The elastodynamic wave equation for an ar-bitrary anisotropic heterogeneous medium is represented by an integral equation of the Lippmann-Schwinger type,with a 9-dimensional wave state(displacement-strain)vector.We solve this higher-dimensional Lippmann-Schwinger equation using a transition operator formalism used in quantum scattering theory.This allows for domain decomposition and novel variational estimates.The tensorial nonlinear inverse scat-tering problem is solved iteratively by using an expression for the Fŕechet derivatives of the scattered wavefield with respect to elastic stiffness tensor fields in terms of modified Green’s functions and wave state vectors that are updated after each iteration.Since the generalized DBIT method is consistent with the Gauss-Newton method,it incorporates approximate Hessian information that is essential for the reduction of multi-parameter cross-talk effects.The DBIT method is implemented efficiently using a variant of the Levenberg-Marquard method,with adaptive selection of the regularization parameter after each iteration.In a series of numerical experiments based on synthetic waveform data for transversely isotropic media with vertical symmetry axes,we obtained a very good match between the true and inverted models when using the traditional Voigt parameterization.This suggests that the effects of cross-talk can be sufficiently reduced by the incorporation of Hessian information and the use of suitable regularization methods.Since the generalized DBIT method for FWI in anisotropic elastic media is naturally target-oriented,it may be particularly suitable for applications to seismic reservoir characterization and monitoring.However,the theory and method presented here is general.

描写翻译研究于翻译批评之重要性

近些年来,中国翻译批评学者不断将各种西方现代翻译理论运用于翻译批评研究,但其中鲜有论及现代翻译研究中最为重要的理论成果描写翻译研究与翻译批评之间的相互关系。本文通过追溯翻译批评从传统到现代发展之轨迹,从学科体系、研究理据、方法构建等角度切入,探寻描写翻译研究与翻译批评在翻译研究学科体系中的地位及其相互之间的联系,以期阐明描写翻译研究于翻译批评之重要性。