Two types of modified silica gels were prepared by adsorption method and bonding method respectively. Enrichment and separation of trace metal ions have been done by using the column packed with modified silica gels.
Considering the discontinuous characteristics of sea ice on various scales,a modified discrete element model（DEM） for sea ice dynamics is developed based on the granular material rheology.In this modified DEM,a soft...Considering the discontinuous characteristics of sea ice on various scales,a modified discrete element model（DEM） for sea ice dynamics is developed based on the granular material rheology.In this modified DEM,a soft sea ice particle element is introduced as a self-adjustive particle size function.Each ice particle can be treated as an assembly of ice floes,with its concentration and thickness changing to variable sizes under the conservation of mass.In this model,the contact forces among ice particles are calculated using a viscous-elastic-plastic model,while the maximum shear forces are described with the Mohr-Coulomb friction law.With this modified DEM,the ice flow dynamics is simulated under the drags of wind and current in a channel of various widths.The thicknesses,concentrations and velocities of ice particles are obtained,and then reasonable dynamic process is analyzed.The sea ice dynamic process is also simulated in a vortex wind field.Taking the influence of thermodynamics into account,this modified DEM will be improved in the future work.展开更多
1. IntroductionA large number of networks for realizing first and second order transfer functions using a currentconveyor have been reported in the literature. Especially, the networks that can offer highinput impedan...1. IntroductionA large number of networks for realizing first and second order transfer functions using a currentconveyor have been reported in the literature. Especially, the networks that can offer highinput impedance attract attention, for high input impedance has the advantage that the networksmay be used in cascade without requiring impedance matching device. In the Higashimura and展开更多
A modified paving technique for automatic generation of all-quadrilateral mesh fromarbitrary 2-D geometry is presented. The generated mesh elementS are nearly square andperpendicular to boundaries. Aner the nodes and...A modified paving technique for automatic generation of all-quadrilateral mesh fromarbitrary 2-D geometry is presented. The generated mesh elementS are nearly square andperpendicular to boundaries. Aner the nodes and elementS formation is completed. a fully automaticgrading method is applied to increase the accuracy and reliability of engineering analysis. In thispaper, we mainly describe the theory of mathematical algorithm and present some examples ofautomatically generated mesh.展开更多
In FLAC ^(3D),cable element or modified pile element can be used to build slope anchoring model.However,the difference between the two structural elements and their influence on the calculation results have not been s...In FLAC ^(3D),cable element or modified pile element can be used to build slope anchoring model.However,the difference between the two structural elements and their influence on the calculation results have not been studied in depth.In order to solve this problem,the Xiashu loess slope anchoring models based on cable element and modified pile element were constructed respectively.A variety of anchoring schemes were designed by orthogonal experiment method,and then they were brought into the model for calculation and the calculation results were analyzed by range analysis and variance analysis.The results show that the modified pile element can bear the bending moment and reflect the strain softening property of the grout.From the perspective of slope safety factor,the anchorage length and anchor bolt spacing are the main factors affecting the stability of the slope,and the anchorage angle is the secondary factor.The grout in cable element is assumed to be an elastic-perfectly plastic material,so the safety factor of the slope can be significantly increased by increasing the length of the anchor bolts.This will bring potential risks to the slope treatment project.Therefore,in the calculation of the slope anchoring model,the modified pile element is more suitable for simulating the anchor bolt.展开更多
In this article, a nonconforming quadrilateral element （named modified quasi- Wilson element） is applied to solve the nonlinear schrSdinger equation （NLSE）. On the basis of a special character of this element, tha...In this article, a nonconforming quadrilateral element （named modified quasi- Wilson element） is applied to solve the nonlinear schrSdinger equation （NLSE）. On the basis of a special character of this element, that is, its consistency error is of order O（ha） for broken Ha-norm on arbitrary quadrilateral meshes, which is two order higher than its interpolation error, the optimal order error estimate and superclose property are obtained. Moreover, the global superconvergence result is deduced with the help of interpolation postprocessing technique. Finally, some numerical results are provided to verify the theoretical analysis.展开更多
In this paper the equivalence of the generalized hybrid element and the modified Wilson element, which is derived by the generalized hybrid method, is proved.
In this work,a modified weak Galerkin finite element method is proposed for solving second order linear parabolic singularly perturbed convection-diffusion equations.The key feature of the proposed method is to replac...In this work,a modified weak Galerkin finite element method is proposed for solving second order linear parabolic singularly perturbed convection-diffusion equations.The key feature of the proposed method is to replace the classical gradient and divergence operators by the modified weak gradient and modified divergence operators,respectively.We apply the backward finite difference method in time and the modified weak Galerkin finite element method in space on uniform mesh.The stability analyses are presented for both semi-discrete and fully-discrete modified weak Galerkin finite element methods.Optimal order of convergences are obtained in suitable norms.We have achieved the same accuracy with the weak Galerkin method while the degrees of freedom are reduced in our method.Various numerical examples are presented to support the theoretical results.It is theoretically and numerically shown that the method is quite stable.展开更多
The static response of two-dimensional horizontal layered piezoelectric bounded domain with side face load was investigated.In this paper,the modified scaled boundary finite element method(SBFEM)is provided as an effe...The static response of two-dimensional horizontal layered piezoelectric bounded domain with side face load was investigated.In this paper,the modified scaled boundary finite element method(SBFEM)is provided as an effective semi analytical methodology.The method is used to solve the static problem for the layered piezoelectric bounded domain.The scaling line definition extends the SBFEM to be more suitable for analyzing the multilayered piezoelectric bounded domain.It avoids the limitations of original SBFEM in modeling the horizontal layered bounded domain.The modified SBFEM governing equation with piezoelectric medium is derived by introducing Duality variable in the Hamilton system.This derivation technology makes the progress be concise.The novel displacement and electric governing equations of the modified SBFEM is given together by the first time.The node forces can be expressed as power exponent function with radial coordinate by introducing the auxiliary variable and using the eigenvalue decomposition.The novel modified SBFEM solution of layered bounded domain with piezoelectric medium is solved.The new power expansion function of layered piezoelectric medium with side face load is proposed.This technology significantly extends the application range of modified SBFEM.The novel treatment of side face load for the layered piezoelectric bounded domain is proposed.Numerical studies are conducted to demonstrate the accuracy of proposed technique in handling with the static problem of layered bounded domain with piezoelectric medium for side face load.The influence of the side face load type and depth are discussed in detail.展开更多
The low accuracy using unstructured meshes to solve complicated geometry problems is a significant challenge in practical engineering.It is the key to solve this issue through enhancing the accuracy of tetrahedral ele...The low accuracy using unstructured meshes to solve complicated geometry problems is a significant challenge in practical engineering.It is the key to solve this issue through enhancing the accuracy of tetrahedral element.This work develops a simple strategy to enhance the accuracy of tetrahedral element with the Shepard interpolation function.In which the strain field is reconstructed by introducing the weighted strains of adjacent tetrahedral elements to central tetrahedral element.The stiffness of the discrete system is significantly softened with this simple operation,which leads to a great accuracy improvement.Furthermore,this simple modification makes linear tetrahedral element owns higher accuracy even compared with hexahedral element.The high precision tetrahedral element makes finite element analysis more acceptable for engineers.It provides a novel solution to finite element analysis using unstructured meshes for practical engineering problems with complicated geometry.In order to validate the accuracy and feasibility of present modified tetrahedral element(M-T4)in complicated geometry problems,several engineering examples are performed,including linear static analysis,modal analysis,frequency response analysis,transient response analysis,and response spectrum analysis.The remarkable performance of the M-T4 suggests its wide applicability to practical engineering problems.展开更多
Laser Interferometer Space Antenna(LISA)is a project to detect and measure gravitational waves.The project has three spacecraft ying in a formation of near equilateral triangle in a heliocentric orbit trailing Earth.M...Laser Interferometer Space Antenna(LISA)is a project to detect and measure gravitational waves.The project has three spacecraft ying in a formation of near equilateral triangle in a heliocentric orbit trailing Earth.Many sources of perturbations cause the con guration to deviate from the nominal.This paper studies the formation design problem for a LISA-like mission by considering ephemeris-based dynamics.This type of mission is well-known for addressing several strict mission requirements under the realistic dynamics.The problem is formulated as optimizing multiple mission performance indices.It is observed that some indices are correlated with each other,whereas some indices have di erent sensitivities with respect to the semi-major axis.Therefore,the problem is transformed into a two-step cascade single-objective optimization,in which the optimal solution of the rst optimization problem is fed to the second optimization as initial value.In addition,the major perturbing celestial bodies are picked up to make a simpli ed but accurate enough dynamics to speed up the optimization.Numerical examples verify the analysis and show the e ectiveness of the optimization procedure.The in uences of mission lifetime and spatial scales on the optimal solutions are also presented.展开更多
文摘Two types of modified silica gels were prepared by adsorption method and bonding method respectively. Enrichment and separation of trace metal ions have been done by using the column packed with modified silica gels.
基金Special Fund of Marine Commonweal Industry under contact Nos 201105016 and 201205007supported by National Marine Environment Forecasting Centrethe National Natural Science Foundation of China under contact No.41176012
文摘Considering the discontinuous characteristics of sea ice on various scales,a modified discrete element model（DEM） for sea ice dynamics is developed based on the granular material rheology.In this modified DEM,a soft sea ice particle element is introduced as a self-adjustive particle size function.Each ice particle can be treated as an assembly of ice floes,with its concentration and thickness changing to variable sizes under the conservation of mass.In this model,the contact forces among ice particles are calculated using a viscous-elastic-plastic model,while the maximum shear forces are described with the Mohr-Coulomb friction law.With this modified DEM,the ice flow dynamics is simulated under the drags of wind and current in a channel of various widths.The thicknesses,concentrations and velocities of ice particles are obtained,and then reasonable dynamic process is analyzed.The sea ice dynamic process is also simulated in a vortex wind field.Taking the influence of thermodynamics into account,this modified DEM will be improved in the future work.
文摘1. IntroductionA large number of networks for realizing first and second order transfer functions using a currentconveyor have been reported in the literature. Especially, the networks that can offer highinput impedance attract attention, for high input impedance has the advantage that the networksmay be used in cascade without requiring impedance matching device. In the Higashimura and
文摘A modified paving technique for automatic generation of all-quadrilateral mesh fromarbitrary 2-D geometry is presented. The generated mesh elementS are nearly square andperpendicular to boundaries. Aner the nodes and elementS formation is completed. a fully automaticgrading method is applied to increase the accuracy and reliability of engineering analysis. In thispaper, we mainly describe the theory of mathematical algorithm and present some examples ofautomatically generated mesh.
基金Project(41672258) supported by the National Natural Science Foundation of ChinaProject(2018045) supported by the Science and Technology Project of Jiangsu Provincial Land and Resources,China。
文摘In FLAC ^(3D),cable element or modified pile element can be used to build slope anchoring model.However,the difference between the two structural elements and their influence on the calculation results have not been studied in depth.In order to solve this problem,the Xiashu loess slope anchoring models based on cable element and modified pile element were constructed respectively.A variety of anchoring schemes were designed by orthogonal experiment method,and then they were brought into the model for calculation and the calculation results were analyzed by range analysis and variance analysis.The results show that the modified pile element can bear the bending moment and reflect the strain softening property of the grout.From the perspective of slope safety factor,the anchorage length and anchor bolt spacing are the main factors affecting the stability of the slope,and the anchorage angle is the secondary factor.The grout in cable element is assumed to be an elastic-perfectly plastic material,so the safety factor of the slope can be significantly increased by increasing the length of the anchor bolts.This will bring potential risks to the slope treatment project.Therefore,in the calculation of the slope anchoring model,the modified pile element is more suitable for simulating the anchor bolt.
基金supported by the National Natural Science Foundation of China(11271340,11101381)
文摘In this article, a nonconforming quadrilateral element （named modified quasi- Wilson element） is applied to solve the nonlinear schrSdinger equation （NLSE）. On the basis of a special character of this element, that is, its consistency error is of order O（ha） for broken Ha-norm on arbitrary quadrilateral meshes, which is two order higher than its interpolation error, the optimal order error estimate and superclose property are obtained. Moreover, the global superconvergence result is deduced with the help of interpolation postprocessing technique. Finally, some numerical results are provided to verify the theoretical analysis.
基金The project is supported by the National Natural Science Foundation of China
文摘In this paper the equivalence of the generalized hybrid element and the modified Wilson element, which is derived by the generalized hybrid method, is proved.
基金supported in part by National Natural Science Foundation of China (No.11871038).
文摘In this work,a modified weak Galerkin finite element method is proposed for solving second order linear parabolic singularly perturbed convection-diffusion equations.The key feature of the proposed method is to replace the classical gradient and divergence operators by the modified weak gradient and modified divergence operators,respectively.We apply the backward finite difference method in time and the modified weak Galerkin finite element method in space on uniform mesh.The stability analyses are presented for both semi-discrete and fully-discrete modified weak Galerkin finite element methods.Optimal order of convergences are obtained in suitable norms.We have achieved the same accuracy with the weak Galerkin method while the degrees of freedom are reduced in our method.Various numerical examples are presented to support the theoretical results.It is theoretically and numerically shown that the method is quite stable.
基金This research was supported by Grants Nos.51409038,51421064,51138001 and 51308307 from the National Natural Science Foundation of ChinaGrant No.GZ1406 from the Open Foundation of State Key Laboratory of Structural Analysis for Industrial Equipment,Grant No.DUT15RC(4)23 from the fundamental research funds for the central universities,and Grant No.YL1610 from the Youth Foundation of State Key Laboratory of Coastal and Offshore Engineering for which the authors are grateful.
文摘The static response of two-dimensional horizontal layered piezoelectric bounded domain with side face load was investigated.In this paper,the modified scaled boundary finite element method(SBFEM)is provided as an effective semi analytical methodology.The method is used to solve the static problem for the layered piezoelectric bounded domain.The scaling line definition extends the SBFEM to be more suitable for analyzing the multilayered piezoelectric bounded domain.It avoids the limitations of original SBFEM in modeling the horizontal layered bounded domain.The modified SBFEM governing equation with piezoelectric medium is derived by introducing Duality variable in the Hamilton system.This derivation technology makes the progress be concise.The novel displacement and electric governing equations of the modified SBFEM is given together by the first time.The node forces can be expressed as power exponent function with radial coordinate by introducing the auxiliary variable and using the eigenvalue decomposition.The novel modified SBFEM solution of layered bounded domain with piezoelectric medium is solved.The new power expansion function of layered piezoelectric medium with side face load is proposed.This technology significantly extends the application range of modified SBFEM.The novel treatment of side face load for the layered piezoelectric bounded domain is proposed.Numerical studies are conducted to demonstrate the accuracy of proposed technique in handling with the static problem of layered bounded domain with piezoelectric medium for side face load.The influence of the side face load type and depth are discussed in detail.
基金supported by the National Key R&D Program of China(No.2022YFB2503505)National Natural Science Foundation of China(No.12002124)+3 种基金National Natural Science Foundation of China(No.12302259)China Postdoctoral Science Foundation(No.2021M690965)Changsha Municipal Natural Science Foundation(No.kq2014035)Natural Science Foundation of Hunan Province(No.2022JJ40031).
文摘The low accuracy using unstructured meshes to solve complicated geometry problems is a significant challenge in practical engineering.It is the key to solve this issue through enhancing the accuracy of tetrahedral element.This work develops a simple strategy to enhance the accuracy of tetrahedral element with the Shepard interpolation function.In which the strain field is reconstructed by introducing the weighted strains of adjacent tetrahedral elements to central tetrahedral element.The stiffness of the discrete system is significantly softened with this simple operation,which leads to a great accuracy improvement.Furthermore,this simple modification makes linear tetrahedral element owns higher accuracy even compared with hexahedral element.The high precision tetrahedral element makes finite element analysis more acceptable for engineers.It provides a novel solution to finite element analysis using unstructured meshes for practical engineering problems with complicated geometry.In order to validate the accuracy and feasibility of present modified tetrahedral element(M-T4)in complicated geometry problems,several engineering examples are performed,including linear static analysis,modal analysis,frequency response analysis,transient response analysis,and response spectrum analysis.The remarkable performance of the M-T4 suggests its wide applicability to practical engineering problems.
基金The work was supported by the Hundred Talents Program of the Chinese Academy of Sciences and Strategic Priority Program A(Grant No.XDA15014902).
文摘Laser Interferometer Space Antenna(LISA)is a project to detect and measure gravitational waves.The project has three spacecraft ying in a formation of near equilateral triangle in a heliocentric orbit trailing Earth.Many sources of perturbations cause the con guration to deviate from the nominal.This paper studies the formation design problem for a LISA-like mission by considering ephemeris-based dynamics.This type of mission is well-known for addressing several strict mission requirements under the realistic dynamics.The problem is formulated as optimizing multiple mission performance indices.It is observed that some indices are correlated with each other,whereas some indices have di erent sensitivities with respect to the semi-major axis.Therefore,the problem is transformed into a two-step cascade single-objective optimization,in which the optimal solution of the rst optimization problem is fed to the second optimization as initial value.In addition,the major perturbing celestial bodies are picked up to make a simpli ed but accurate enough dynamics to speed up the optimization.Numerical examples verify the analysis and show the e ectiveness of the optimization procedure.The in uences of mission lifetime and spatial scales on the optimal solutions are also presented.
