The conventional method of seismic data acquisition geometry design is based on the assumption of horizontal subsurface reflectors, which often is not suitable for complex structure. We start from a controlled illumin...The conventional method of seismic data acquisition geometry design is based on the assumption of horizontal subsurface reflectors, which often is not suitable for complex structure. We start from a controlled illumination analysis and put forward a method of seismic survey geometry design for target-oriented imaging. The method needs a velocity model obtained by a preliminary seismic interpretation. The one-way Fourier finite-difference wave propagator is used to extrapolate plane wave sources on the target layer to the surface. By analyzing the wave energy distribution at the surface extrapolated from the target layer, the shot or receiver locations needed for target layer imaging can be determined. Numerical tests using the SEG-EAGE salt model suggest that this method is useful for confirming the special seismic acquisition geometry layout for target-oriented imaging.展开更多
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 dep...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.展开更多
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 a...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.展开更多
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 ex...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.展开更多
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" pro...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-展开更多
This paper discusses Skopos theory as a general theory in terms of its applicability to real life conditions by developing a questionnaire to assess both the theory itself, and the real life practices fulfilled by the...This paper discusses Skopos theory as a general theory in terms of its applicability to real life conditions by developing a questionnaire to assess both the theory itself, and the real life practices fulfilled by the professional translators. Skopos theory, as the best model that serves to the ends of professional translators, is taken as a basis for developing a logical framework of a research model. Within this context, the function of questionnaires in theoretical research is studied in such a way not only as to bridge the gap between practice and theory, but also in terms of their potentiality in yielding a causal research. In conclusion, this paper aims not only to unravel the ambiguous network between professional research conducted in translation process and questionnaires as tools of research, but it also discusses theoretical knowledge in terms of the logical framework they submit in research展开更多
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 ...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.展开更多
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 ...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展开更多
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 computationa...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.展开更多
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 mul...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.展开更多
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...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.展开更多
文摘The conventional method of seismic data acquisition geometry design is based on the assumption of horizontal subsurface reflectors, which often is not suitable for complex structure. We start from a controlled illumination analysis and put forward a method of seismic survey geometry design for target-oriented imaging. The method needs a velocity model obtained by a preliminary seismic interpretation. The one-way Fourier finite-difference wave propagator is used to extrapolate plane wave sources on the target layer to the surface. By analyzing the wave energy distribution at the surface extrapolated from the target layer, the shot or receiver locations needed for target layer imaging can be determined. Numerical tests using the SEG-EAGE salt model suggest that this method is useful for confirming the special seismic acquisition geometry layout for target-oriented imaging.
文摘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.
基金supported by the National Key R&D Program of China(2021YFA0716902)National Natural Science Foundation of China(42004119,42174156)+1 种基金the Fundamental Research Funds for the Central Universities,CHD(300102261306)the National Engineering Research Center of Offshore Oil and Gas Exploration,No.6 Courtyard,Taiyanggong South Street,Chaoyang District,Beijing,100028.
文摘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.
基金This work was supported by the Major Program of the National Natural Science Foundation of China(No.51835006)Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52021003).
文摘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.
文摘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-
文摘This paper discusses Skopos theory as a general theory in terms of its applicability to real life conditions by developing a questionnaire to assess both the theory itself, and the real life practices fulfilled by the professional translators. Skopos theory, as the best model that serves to the ends of professional translators, is taken as a basis for developing a logical framework of a research model. Within this context, the function of questionnaires in theoretical research is studied in such a way not only as to bridge the gap between practice and theory, but also in terms of their potentiality in yielding a causal research. In conclusion, this paper aims not only to unravel the ambiguous network between professional research conducted in translation process and questionnaires as tools of research, but it also discusses theoretical knowledge in terms of the logical framework they submit in research
基金This work was supported by Shaanxi Science and Technology Projects(2017KJXX-54 and 2014KTCL02-15)Science and Technology Project of Northwest A&F University(Z222021560)the"Young Faculty Study Abroad Program"of Northwest A&F University Scholarship Fund.
文摘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.
基金supported by the National Science and Technology Major Project for Major Drug Development(No.2013ZX09508104)the Traditional Chinese Medicine Industry Research Special Project(No.201307002)the National Science&Technology Major Project Key New Drug Creation and Manufacturing program(No.2011ZX09307002-03)of the People's Republic of China
文摘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
文摘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.
文摘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.
文摘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.
