摘要 :
The principle of microscopic scattering dark-field imaging is adopted in surface defects evaluation system (SDES) for large fine optics. However, since defects are of micron or submicron scale, scattering imaging cannot be describ...
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The principle of microscopic scattering dark-field imaging is adopted in surface defects evaluation system (SDES) for large fine optics. However, since defects are of micron or submicron scale, scattering imaging cannot be described simply by geometrical imaging. In this paper, the simulation model of the electromagnetic field in defect scattering imaging is established on the basis of Finite-Difference Time-Domain (FDTD) method to study the scattering imaging properties of rectangular and triangular defects with different sizes by simulation. The criterion board with scribed lines and dots on it is used to carry out experiments scattering imaging and obtain grayscale value distributions of scattering dark-field images of scribed lines. The experiment results are in good agreement with the simulation results. Based on the above analysis, defect width extraction width is preliminary discussed. Findings in this paper could provide theoretical references for defect calibration in optical fabrication and inspection.
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摘要 :
The principle of microscopic scattering dark-field imaging is adopted in surface defects evaluation system (SDES) for large fine optics. However, since defects are of micron or submicron scale, scattering imaging cannot be describ...
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The principle of microscopic scattering dark-field imaging is adopted in surface defects evaluation system (SDES) for large fine optics. However, since defects are of micron or submicron scale, scattering imaging cannot be described simply by geometrical imaging. In this paper, the simulation model of the electromagnetic field in defect scattering imaging is established on the basis of Finite-Difference Time-Domain (FDTD) method to study the scattering imaging properties of rectangular and triangular defects with different sizes by simulation. The criterion board with scribed lines and dots on it is used to carry out experiments scattering imaging and obtain grayscale value distributions of scattering dark-field images of scribed lines. The experiment results are in good agreement with the simulation results. Based on the above analysis, defect width extraction width is preliminary discussed. Findings in this paper could provide theoretical references for defect calibration in optical fabrication and inspection.
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We have previously introduced a transformation based upon the Fast Marching Methods (FMM) to describe the multi-dimensional diffusivity equation with heterogeneity as an effective one dimensional diffusivity equation in a streamtu...
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We have previously introduced a transformation based upon the Fast Marching Methods (FMM) to describe the multi-dimensional diffusivity equation with heterogeneity as an effective one dimensional diffusivity equation in a streamtube. In the current study we develop and validate new asymptotic analytic approximations to this problem, which provide for a number of novel applications including rapid numerical simulation, reservoir and well characterization, sensitivity-based inversion using production data, and dynamic upscaling and downscaling. The novel semi-analytic asymptotic pressure approximation for the solution of an equivalent 1-D diffusivity equation is able to approximate the 3-D solution with heterogeneity. Earlier approaches have relied upon the numerical solution of the 1-D equation, and provide all the flexibility expected of a numerical approach. However, analytic solutions provide for the derivation of explicit relationships between the geometry of a propagating pressure "front" within a reservoir and pressure and rate measured at wells. In the current study, we extend the analytic treatment beyond simple fixed rate draw-down and test the predictions against analytic and numerical synthetic cases. In this paper we provide a systemic validation of our semi-analytic solution technique and extend its utility to more realistic cases, including large changes in reservoir properties, pressure transient analysis with wellbore storage, and rate transient analysis in bounded reservoirs with fixed rate or fixed BHP production. This technique provides us with the ability to describe pressure propagation from fractured wells into the surrounding formations, which provides for a better drainage volume characterization, which is beneficial for both well spacing calculation and multi-stage fracture spacing optimization in unconventional reservoirs. It not only provides for the direct calculation of various welltest, rate transient and well performance concepts such as depth of investigation, welltest derivative, flow regimes and well productivity, but it can also predict pressure and flux distribution maps at any time of interest. Our study verifies that the new approach yields results very close to those generated by commercial simulators, indicating its promising application to rapid field production data analysis. As with other analytic approaches, the derived asymptotic solutions satisfy superposition in space and time, which allows for further application to cases with multiple wells and varying flow rates. We show the validation of novel semi-analytic asymptotic pressure solutions to the diffusivity equation, which extend the calculation of rate and pressure transient from homogeneous reservoirs with regular well geometries to a series of reservoir problems with hydraulic fractured wells and reservoir heterogeneity. The treatment we present in this paper is faster than numerical finite difference simulation and allows for the development of fundamental relationships between reservoir performance and reservoir and well characteristics.
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摘要 :
We have previously introduced a transformation based upon the Fast Marching Methods (FMM) to describe the multi-dimensional diffusivity equation with heterogeneity as an effective one dimensional diffusivity equation in a streamtu...
展开
We have previously introduced a transformation based upon the Fast Marching Methods (FMM) to describe the multi-dimensional diffusivity equation with heterogeneity as an effective one dimensional diffusivity equation in a streamtube. In the current study we develop and validate new asymptotic analytic approximations to this problem, which provide for a number of novel applications including rapid numerical simulation, reservoir and well characterization, sensitivity-based inversion using production data, and dynamic upscaling and downscaling. The novel semi-analytic asymptotic pressure approximation for the solution of an equivalent 1-D diffusivity equation is able to approximate the 3-D solution with heterogeneity. Earlier approaches have relied upon the numerical solution of the 1-D equation, and provide all the flexibility expected of a numerical approach. However, analytic solutions provide for the derivation of explicit relationships between the geometry of a propagating pressure "front" within a reservoir and pressure and rate measured at wells. In the current study, we extend the analytic treatment beyond simple fixed rate draw-down and test the predictions against analytic and numerical synthetic cases. In this paper we provide a systemic validation of our semi-analytic solution technique and extend its utility to more realistic cases, including large changes in reservoir properties, pressure transient analysis with wellbore storage, and rate transient analysis in bounded reservoirs with fixed rate or fixed BHP production. This technique provides us with the ability to describe pressure propagation from fractured wells into the surrounding formations, which provides for a better drainage volume characterization, which is beneficial for both well spacing calculation and multi-stage fracture spacing optimization in unconventional reservoirs. It not only provides for the direct calculation of various welltest, rate transient and well performance concepts such as depth of investigation, welltest derivative, flow regimes and well productivity, but it can also predict pressure and flux distribution maps at any time of interest. Our study verifies that the new approach yields results very close to those generated by commercial simulators, indicating its promising application to rapid field production data analysis. As with other analytic approaches, the derived asymptotic solutions satisfy superposition in space and time, which allows for further application to cases with multiple wells and varying flow rates. We show the validation of novel semi-analytic asymptotic pressure solutions to the diffusivity equation, which extend the calculation of rate and pressure transient from homogeneous reservoirs with regular well geometries to a series of reservoir problems with hydraulic fractured wells and reservoir heterogeneity. The treatment we present in this paper is faster than numerical finite difference simulation and allows for the development of fundamental relationships between reservoir performance and reservoir and well characteristics.
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In this paper, the characteristics and current situation of heavy metal pollution in farmland in China, the influencing factors and mechanism of heavy metal pollution in crops, the summary of remote sensing monitoring methods for ...
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In this paper, the characteristics and current situation of heavy metal pollution in farmland in China, the influencing factors and mechanism of heavy metal pollution in crops, the summary of remote sensing monitoring methods for heavy metal pollution in farmland and the research prospect are discussed. Farmland non-point source pollution monitoring is an important issue related to national security and stability and people's livelihood. At present, the characteristics of heavy metal pollution in farmland in China mainly include:①Heavy metal pollution is prevalent in soils.The three major rice dominant areas in China (the rice dominant area in the northeast plain, the rice dominant area in the Yangtze river basin, and the rice dominant area in the southeast coast) are all polluted by heavy metals to varying degrees. ②Heavy metal pollution is serious in farmland. The pollutants are mainly As, Cd, Pb, Hg, Ni, Cu, DDT and pahs.③Heavy metal contamination of grain occurs frequently. Heavy metal polluted farmland may cause crop diseases. In this paper, the spatial distribution characteristics of As. Cu, Cd. Cr. Pb and Zn in China are summarized. The content of heavy metal elements in crops largely depends on the characteristics and types of crops as well as the growing environment.
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摘要 :
In this paper, the characteristics and current situation of heavy metal pollution in farmland in China, the influencing factors and mechanism of heavy metal pollution in crops, the summary of remote sensing monitoring methods for ...
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In this paper, the characteristics and current situation of heavy metal pollution in farmland in China, the influencing factors and mechanism of heavy metal pollution in crops, the summary of remote sensing monitoring methods for heavy metal pollution in farmland and the research prospect are discussed. Farmland non-point source pollution monitoring is an important issue related to national security and stability and people's livelihood. At present, the characteristics of heavy metal pollution in farmland in China mainly include:①Heavy metal pollution is prevalent in soils.The three major rice dominant areas in China (the rice dominant area in the northeast plain, the rice dominant area in the Yangtze river basin, and the rice dominant area in the southeast coast) are all polluted by heavy metals to varying degrees. ②Heavy metal pollution is serious in farmland. The pollutants are mainly As, Cd, Pb, Hg, Ni, Cu, DDT and pahs.③Heavy metal contamination of grain occurs frequently. Heavy metal polluted farmland may cause crop diseases. In this paper, the spatial distribution characteristics of As. Cu, Cd. Cr. Pb and Zn in China are summarized. The content of heavy metal elements in crops largely depends on the characteristics and types of crops as well as the growing environment.
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This study compares the convective time-of-flight(calculated using the Complex Analysis Method,CAM)and the diffusive time-of-flight(calculated using the Fast Marching Method,FMM)in unconventional reservoir models.The convective ti...
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This study compares the convective time-of-flight(calculated using the Complex Analysis Method,CAM)and the diffusive time-of-flight(calculated using the Fast Marching Method,FMM)in unconventional reservoir models.The convective time-of-flight determines the drained rock volume(DRV),which refers to the volume of reservoir rock actually drained due to production.The diffusive time-of-flight determines the propagation of the pressure front,which corresponds to the extent of the drainage volume and leads to various definitions such as the depth of investigation,the limit of detectability and the stabilized zone in the reservoir.The disparity(or lag zone)between the DRV and the drainage volume is quantified for a declining production rate in a modeled shale reservoir.The combined strengths of FMM and CAM are applied to calculate the dynamic growth of the pressure and convective tracer fronts during transient flow around the hydraulic fractures of a multi-stage fractured horizontal well,using data generated from a numerical simulator.The synthetic model uses reservoir and completion parameters typical for wells in unconventional shale reservoirs.Comparison of the DRV from CAM and the drainage volume from FMM shows the extent of the lag zone between the propagating pressure front and the tracer front to be of a large magnitude.A crucial insight is that reservoir areas that are under-going pressure depletion(as shown by the diffusive time-of-flight)will still have significant hydrocarbon volumes present in the reservoir space outside of the calculated DRV.Beyond instantaneous production based diagnostic plots of DRV and drainage volumes,FMM and CAM are used to create flow visualizations to provide a spatial description of these propagating fronts in the reservoir.Novel use of FMM and CAM also allows for insight in recovery factors and instantaneous recovery ratios in unconventional reservoirs.
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The complexity of the multiplication operation over polynomial rings and finite fields drastically changes with the selection of the defining polynomial of the respective mathematical structure. Trinomials and pentanomials are the...
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The complexity of the multiplication operation over polynomial rings and finite fields drastically changes with the selection of the defining polynomial of the respective mathematical structure. Trinomials and pentanomials are the most natural choices for the best arithmetic. In this paper, we first present a study in which a special type of trinomial does not require any reduction steps. We then introduce two new algorithms, FIKO and RF-PIKO, fully interleaved bit-parallel Karatsuba-Ofman multipliers where the latter is only concerned with the three Karatsuba-Ofman terms and is free from the bipartite reduction circuits. All algorithms are implemented in FPGA and ASIC, and detailed implementation results are presented, showing significant improvements to existing methods.
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